Wednesday, July 3, 2013
SUDOKU, PUZZLES
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Free math problem solver
Free math problem solver
The free math problem solver below is a sophisticated tool that will solve any math problems you enter quickly and then show you the answer.
I recommend that you use it only to check your own work because occasionally, it might generate strange results
After you enter your math problems, click on "Math Format" to make sure you have effectively entered the math problem you really want it to solve
You can also enter word problems, but don't be too fancy. Use plenty of math operators and keep it as simple as possible
If you want step by step solution after the final answer is entered, click on "View Steps"
This will take you to the developer's site where you sign in. A modest fee may be required to view all steps
Enjoy this online math problem solver!
Need a math tutor?
Get an answer in 10 minutes or less from a math expert!
Get an answer in 10 minutes or less from a math expert!
Justanswer features top-notch math experts handpicked by personnel after they have taken and passed a rigourous math test and after their credentials have been verified by a third party
Most math experts have bachelor's or master's degree in math or a related field
I am also an expert for justanswer. If you want me to answer your questions, sign in, browse the list of math experts, select my name or ask for me (Jetser Carasco) before sending your question(s)
The formula for percentage is the following and it should be easy to use
The formula for percentage is the following and it should be easy to use:
Study it below carefully before looking at the examples
We will take examples to illustrate.Let us start with the formula on the left
An important thing to remember: Cross multiply
It means to multiply the numerator of one fraction by the denominator of the other fraction
Examples #1:
25 % of 200 is____
In this problem, of = 200, is = ?, and % = 25
We get:
is/200 = 25/100
Since is in an unknown, you can replace it by y to make the problem more familiar
y/200 = 25/100
Cross multiply to get y × 100 = 200 × 25
y × 100 = 5000
Divide 5000 by 100 to get y
Since 5000/100 = 50, y = 50
So, 25 % of 200 is 50
Examples #2:
What number is 2% of 50 ?
This is just another way of saying 2% of 50 is___
So, set up the proportion as example #1:
is/50 = 2/100
Replace is by y and cross multiply to get:
y × 100 = 50 × 2
y × 100 = 100
Since 1 × 100 = 100, y = 1
Therefore, 1 is 2 % of 50
Examples #3:
24% of___ is 36
This time, notice that is = 36, but of is missing
After you set up the formula, you get:
36/of = 24/100
Replace of by y and cross multiply to get:
36/y = 24/100
y × 24 = 36 × 100
y × 24 = 3600
Divide 3600 by 24 to get y
3600/24 = 150, y = 150
Therefore, 24 % of 150 is 36
Now, we will take examples to illustrate how to use the formula for percentage on the right
Examples #4:
To use the other formula that says part and whole, just remember the following:
The number after of is always the whole
The number after is is always the part
If I say 25 % of___ is 60, we know that the whole is missing and part = 60
Your proportion will will like this:
60/whole = 25/100
After cross multiplying, we get:
whole × 25 = 60 × 100
whole × 25 = 6000
Divide 6000 by 25 to get whole
6000/25 = 240, so whole = 240
Therefore, 25 % of 240 is 60
Examples #5:
___% of 45 is 9
Here whole = 45 and part = 9, but % is missing
We get:
9/45 = %/100
Replacing % by x and cross multiplying gives:
9 × 100 = 45 × x
900 = 45 × x
Divide 900 by 45 to get x
900/45 = 20, so x = 20
Here we go!. I hope these formula for percentage were helpful.
We will take examples to illustrate.Let us start with the formula on the left
An important thing to remember: Cross multiply
It means to multiply the numerator of one fraction by the denominator of the other fraction
Examples #1:
25 % of 200 is____
In this problem, of = 200, is = ?, and % = 25
We get:
is/200 = 25/100
Since is in an unknown, you can replace it by y to make the problem more familiar
y/200 = 25/100
Cross multiply to get y × 100 = 200 × 25
y × 100 = 5000
Divide 5000 by 100 to get y
Since 5000/100 = 50, y = 50
So, 25 % of 200 is 50
Examples #2:
What number is 2% of 50 ?
This is just another way of saying 2% of 50 is___
So, set up the proportion as example #1:
is/50 = 2/100
Replace is by y and cross multiply to get:
y × 100 = 50 × 2
y × 100 = 100
Since 1 × 100 = 100, y = 1
Therefore, 1 is 2 % of 50
Examples #3:
24% of___ is 36
This time, notice that is = 36, but of is missing
After you set up the formula, you get:
36/of = 24/100
Replace of by y and cross multiply to get:
36/y = 24/100
y × 24 = 36 × 100
y × 24 = 3600
Divide 3600 by 24 to get y
3600/24 = 150, y = 150
Therefore, 24 % of 150 is 36
Now, we will take examples to illustrate how to use the formula for percentage on the right
Examples #4:
To use the other formula that says part and whole, just remember the following:
The number after of is always the whole
The number after is is always the part
If I say 25 % of___ is 60, we know that the whole is missing and part = 60
Your proportion will will like this:
60/whole = 25/100
After cross multiplying, we get:
whole × 25 = 60 × 100
whole × 25 = 6000
Divide 6000 by 25 to get whole
6000/25 = 240, so whole = 240
Therefore, 25 % of 240 is 60
Examples #5:
___% of 45 is 9
Here whole = 45 and part = 9, but % is missing
We get:
9/45 = %/100
Replacing % by x and cross multiplying gives:
9 × 100 = 45 × x
900 = 45 × x
Divide 900 by 45 to get x
900/45 = 20, so x = 20
Here we go!. I hope these formula for percentage were helpful.
Basic math test
Basic math formulas
Find here a comprehensive list of basic math formulas commonly used when doing basic math computation
Let a1,a2,a3,......,an be a set of numbers, average = (a1 + a2 + a3,+......+ an)/n
Fractions formulas:
Converting a mixed number to an improper fraction:
Converting an improper fraction to a mixed number:
Formula for a proportion:
In a proportion, the product of the extremes (ad) equal the product of the means(bc),
Thus, ad = bc
Percent:
Percent to fraction: x% = x/100
Percentage formula: Rate/100 = Percentage/base
Rate: The percent.
Base: The amount you are taking the percent of.
Percentage: The answer obtained by multiplying the base by the rate
Consumer math formulas:
Discount = list price × discount rate
Sale price = list price − discount
Discount rate = discount ÷ list price
Sales tax = price of item × tax rate
Interest = principal × rate of interest × time
Tips = cost of meals × tip rate
Commission = cost of service × commission rate
Geometry formulas:
Perimeter:
Perimeter of a square: s + s + s + s
s:length of one side
Perimeter of a rectangle: l + w + l + w
l: length
w: width
Perimeter of a triangle: a + b + c
a, b, and c: lengths of the 3 sides
Area:
Area of a square: s × s
s: length of one side
Area of a rectangle: l × w
l: length
w: width
Area of a triangle: (b × h)/2
b: length of base
h: length of height
Area of a trapezoid: (b1 + b2) × h/2
b1 and b2: parallel sides or the bases
h: length of height
volume:
Volume of a cube: s × s × s
s: length of one side
Volume of a box: l × w × h
l: length
w: width
h: height
Volume of a sphere: (4/3) × pi × r3
pi: 3.14
r: radius of sphere
Volume of a triangular prism: area of triangle × Height = (1/2 base × height) × Height
base: length of the base of the triangle
height: height of the triangle
Height: height of the triangular prism
Volume of a cylinder:pi × r2 × Height
pi: 3.14
r: radius of the circle of the base
Height: height of the cylinder
Have any questions about the basic math formulas? Send me an email here and ask me any questions you want about these basic math formulas
Related topics:
Really Hard Riddles
Top 20 Really Hard Riddles
Really Hard Riddles 1 : September Riddle
Difficulty ★★★★☆ Popularity ★★★☆☆
man gave one son 10 cents and another son was given 15 cents. What time is it?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 2 : Famous Probability puzzle SHOOT
Difficulty ★★★★☆ Popularity ★★★★☆
Mr. Black, Mr. Gray, and Mr. White are fighting in a truel. They each get a gun and take turns shooting at each other until only one person is left. Mr. Black, who hits his shot 1/3 of the time, gets to shoot first. Mr. Gray, who hits his shot 2/3 of the time, gets to shoot next, assuming he is still alive. Mr. White, who hits his shot all the time, shoots next, assuming he is also alive. The cycle repeats. If you are Mr. Black, where should you shoot first for the highest chance of survival?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 3 : Writers Riddle
Difficulty ★★★★☆ Popularity ★★★★☆
What work can one never finish?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 4 : Aeroplane Hijack puzzle
Difficulty ★★★★★ Popularity ★★★★☆
A man hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 5 : Cipher Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
What does this message say?
G T Y O R J O T E O U I A B G T
Hint
Count the letters and try splitting the letters up into groups.
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 6 : Pyramid Number Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
The below is a number puzzle. It should be read left to right, top to bottom.
1
1 1
2 1
1 2 1 1
1 1 1 2 2 1
? ? ? ? ? ?
? ? ? ? ? ? ? ?
Question 1: What is the next two rows of numbers?
Question 2: How was this reached?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 7 : Unique Riddle
Difficulty ★★★★★ Popularity ★★★☆☆
What is the unique characteristic of the following words:
coughing, thirsty, defiant
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 8 : CAT EXAM Riddle
Difficulty ★★★★☆ Popularity ★★★★☆
There is a shop that reads:
Buy 1 for $1.00
10 for $2.00
100 for $3.00
I needed 913 and still only paid $3.00. How could this be financially viable for the shop-keeper?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 9 : What Am I Puzzle
Difficulty ★★★★☆ Popularity ★★★★☆
If you throw me from the window,
I will leave a grieving wife.
Bring me back, but in the door, and
You'll see someone giving life!
What am I?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 10 : Mathematical Riddle
Difficulty ★★★★★ Popularity ★★★☆☆
Using only two 2's and any combination of mathematical signs, symbols and functions can you make 5?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 11 : Famous Elevator Puzzle
Difficulty ★★★★☆ Popularity ★★★★☆
A man who lives on the tenth floor takes the elevator down to the first floor every morning and goes to work. In the evening, when he comes back; on a rainy day, or if there are other people in the elevator, he goes to his floor directly. Otherwise, he goes to the seventh floor and walks up three flights of stairs to his apartment.
Can you explain why?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 12 : Mystery Puzzle Sherlock Holmes
Difficulty ★★★★☆ Popularity ★★★☆☆
One snowy night, Sherlock Holmes was in his house sitting by a fire. All of a sudden a snowball came crashing through his window, breaking it. Holmes got up and looked out the window just in time to see three neighborhood kids who were brothers run around a corner. Their names were John Crimson, Mark Crimson and Paul Crimson.
The next day Holmes got a note on his door that read '? Crimson. He broke your window.'
Which of the three Crimson brothers should Sherlock Holmes question about the incident?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 13 : Which Is The Odd One Out
Difficulty ★★★★★ Popularity ★★★☆☆
Find The Odd One Out
1.FLOW
2.SNIP
3.TRAP
4.DRAW
5.BACK
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 14 : Answer This Joke Riddle
Difficulty ★★★★☆ Popularity ★★★★★
Why is 6 afraid of 7?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 15 : Hard Math Riddle
Difficulty ★★★★☆ Popularity ★★★★★
Take 9 from 6, 10 from 9, 50 from 40 and leave 6.
How Come ??
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 16 : Death Mystery Riddle
Difficulty ★★★★☆ Popularity ★★★★☆
Two men are in a desert. They both have packs on. One of the guys is dead. The guy who is alive has his pack open, the guy who is dead has his pack closed. What is in the pack?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 17 : Hardest Math Riddle
Difficulty ★★★★★ Popularity ★★★★★
Create a number using only the digits 4,4,3,3,2,2,1 and 1. So i can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 18 : Puzzle In A Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
What are the next two letters in the following series and why?
W A T N T L I T F S _ _
*Hint: Check Puzzle Title
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 19 : Alexander Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
Alexander is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.
There are cliffs around the island, so he cannot jump off.
How can the Alexander survive the fire? (There are no buckets or any other means to put out the fire)
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 20 : Challenging Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
Outside a room there are three light switches. One of switch is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.
You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)
Your task is to then determine which switch controls the bulb ??
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 1 : September Riddle
Difficulty ★★★★☆ Popularity ★★★☆☆
man gave one son 10 cents and another son was given 15 cents. What time is it?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 2 : Famous Probability puzzle SHOOT
Difficulty ★★★★☆ Popularity ★★★★☆
Mr. Black, Mr. Gray, and Mr. White are fighting in a truel. They each get a gun and take turns shooting at each other until only one person is left. Mr. Black, who hits his shot 1/3 of the time, gets to shoot first. Mr. Gray, who hits his shot 2/3 of the time, gets to shoot next, assuming he is still alive. Mr. White, who hits his shot all the time, shoots next, assuming he is also alive. The cycle repeats. If you are Mr. Black, where should you shoot first for the highest chance of survival?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 3 : Writers Riddle
Difficulty ★★★★☆ Popularity ★★★★☆
What work can one never finish?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 4 : Aeroplane Hijack puzzle
Difficulty ★★★★★ Popularity ★★★★☆
A man hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 5 : Cipher Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
What does this message say?
G T Y O R J O T E O U I A B G T
Hint
Count the letters and try splitting the letters up into groups.
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 6 : Pyramid Number Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
The below is a number puzzle. It should be read left to right, top to bottom.
1
1 1
2 1
1 2 1 1
1 1 1 2 2 1
? ? ? ? ? ?
? ? ? ? ? ? ? ?
Question 1: What is the next two rows of numbers?
Question 2: How was this reached?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 7 : Unique Riddle
Difficulty ★★★★★ Popularity ★★★☆☆
What is the unique characteristic of the following words:
coughing, thirsty, defiant
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 8 : CAT EXAM Riddle
Difficulty ★★★★☆ Popularity ★★★★☆
There is a shop that reads:
Buy 1 for $1.00
10 for $2.00
100 for $3.00
I needed 913 and still only paid $3.00. How could this be financially viable for the shop-keeper?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 9 : What Am I Puzzle
Difficulty ★★★★☆ Popularity ★★★★☆
If you throw me from the window,
I will leave a grieving wife.
Bring me back, but in the door, and
You'll see someone giving life!
What am I?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 10 : Mathematical Riddle
Difficulty ★★★★★ Popularity ★★★☆☆
Using only two 2's and any combination of mathematical signs, symbols and functions can you make 5?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 11 : Famous Elevator Puzzle
Difficulty ★★★★☆ Popularity ★★★★☆
A man who lives on the tenth floor takes the elevator down to the first floor every morning and goes to work. In the evening, when he comes back; on a rainy day, or if there are other people in the elevator, he goes to his floor directly. Otherwise, he goes to the seventh floor and walks up three flights of stairs to his apartment.
Can you explain why?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 12 : Mystery Puzzle Sherlock Holmes
Difficulty ★★★★☆ Popularity ★★★☆☆
One snowy night, Sherlock Holmes was in his house sitting by a fire. All of a sudden a snowball came crashing through his window, breaking it. Holmes got up and looked out the window just in time to see three neighborhood kids who were brothers run around a corner. Their names were John Crimson, Mark Crimson and Paul Crimson.
The next day Holmes got a note on his door that read '? Crimson. He broke your window.'
Which of the three Crimson brothers should Sherlock Holmes question about the incident?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 13 : Which Is The Odd One Out
Difficulty ★★★★★ Popularity ★★★☆☆
Find The Odd One Out
1.FLOW
2.SNIP
3.TRAP
4.DRAW
5.BACK
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 14 : Answer This Joke Riddle
Difficulty ★★★★☆ Popularity ★★★★★
Why is 6 afraid of 7?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 15 : Hard Math Riddle
Difficulty ★★★★☆ Popularity ★★★★★
Take 9 from 6, 10 from 9, 50 from 40 and leave 6.
How Come ??
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 16 : Death Mystery Riddle
Difficulty ★★★★☆ Popularity ★★★★☆
Two men are in a desert. They both have packs on. One of the guys is dead. The guy who is alive has his pack open, the guy who is dead has his pack closed. What is in the pack?
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 17 : Hardest Math Riddle
Difficulty ★★★★★ Popularity ★★★★★
Create a number using only the digits 4,4,3,3,2,2,1 and 1. So i can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 18 : Puzzle In A Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
What are the next two letters in the following series and why?
W A T N T L I T F S _ _
*Hint: Check Puzzle Title
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 19 : Alexander Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
Alexander is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.
There are cliffs around the island, so he cannot jump off.
How can the Alexander survive the fire? (There are no buckets or any other means to put out the fire)
For Answers/Discussion : Click Here
==============================================
Really Hard Riddles 20 : Challenging Puzzle
Difficulty ★★★★☆ Popularity ★★★★★
Outside a room there are three light switches. One of switch is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.
You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)
Your task is to then determine which switch controls the bulb ??
For Answers/Discussion : Click Here
==============================================
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