Can You Do These 5th-Grade Math Problems in Your Head?

Add the single digits together first to get 11. Then carry the one to get a "2" in the 10's place and a "1" in the one's place.

This one is easy to do in your head. Subtract the single digits of both numbers to get 3-2 =1 and subtract the double digits or 5-2 =3. So the answer is 31.

This should have been easy because 3 x 5 = 15, so 3 goes into 15 five times.

These types of math problems are easy to do in your head when you don't need to carry numbers into the next column. The answer is 88.

First reduce the amount so it's just labor by taking out the cost of supplies or $330 - $225 = $105. Then divide the total cost of labor by the cost per hour or $35 to get $105 ÷ $35 = 3 hours

As long as you have a common denominator, you can subtract the two numerators and leave the denominator as is.

Be sure to remember where to keep the decimal point. That tip will come in handy later on.

Divide the number until you can't divide anymore. The result will be lots of small numbers and a prime number or the smallest non-prime number.

The 10 days is an added fact that doesn't help solve the problem. There are 3 sheds built and 7 workers, so each worker built 3/7 of a shed.

There are three zeros in one thousand. So move the decimal three places to the right to get the correct answer.

There are 60 minutes in an hour, and 24 hours in a day. So it's easier to multiply 24 x 6 = 144 and then add the 0 at the end to get 1,440. Next, multiply those minutes by 7 to get 10,080.

Here is an example of how it's easier to add 50 rather than 49. So take 1 from 113 to make 112 and add that 1 to 49. The new, easier-to-add equation is 112 + 50 = 162.

As a refresher, you round up with a "5". Also the 100 place is the third place to the left of the decimal point so 755 will be 800. So the answer is 8,800.

Imagining the 8 subtracted by 8 is easy. But subtracting the 9 from 7 might have been a little harder. Too easy for you? Hang in there. This quiz gets progressively harder.

Justin walks 4 kilometers an hour. So in 4 hours, he walks 16 kilometers (4 x 4 = 16) But he needs to walk 18 kilometers, so there are 2 kilometers left to walk at 4 kilometers an hour, or 2/4 which can be reduced to 1/2 hour. So the answer is 4.5 hours.

The easiest way to do this in your head is to multiply 2 x 17 = 34. Then add a zero to the sum to get 340.

This problem is all about reducing until you have the lowest common denominator. First, divide both numerator and denominator by 3 to get 8/12 - 2/3. Now reduce the first fraction by dividing top and bottom by 4, so you have 2/3. The final equation is 2/3 -2/3 = 0

Ask yourself how many times does 44 go into 176; the answer is 4, which you need to multiply the denominator by to get 400. The same operation is used in the second equivalency equation.

Convert a pizza and a half into quarters. (4 quarters = 1) So 6 quarters = a pizza and a half. Then, one quarter = 1 minute to be eaten, so 6 quarters = 6 minutes to eat.

The number 93 when divided by 5 is 18 with a remainder of 3. When you divide 3.0 by 5 you get .6. So the answer is 18.6.

Now remember, no calculator allowed. (But we won't tell if you used a #2 pencil.) Just keep the decimals where they are and do the subtraction to get the right answer.

Reduce the fractions to make them manageable. 14/42 = 1/3, and 15/75 = 1/5. So the equation now reads 1/3 - 1/5 = ? So cross multiply to get the common denominator or 5/15 - 3/15 = 2/15.

If x = toys, then Bob has (5 + x) and Tom has x. Put this into an equation so that (5 + x) + x = 49. Subtract 5 from each side of the equation and get x + x = 44 or 2x = 44 or x = 22. Put x back into the equation and Bob has 27 and Tom has 22.

Reducing the fractions you get 1/8 + 5/8 = 6/8 then reduce the answer to 3/4 or .75. It's all about reducing numbers until they are easier to work with in your head.

The decimal sign moves to the right one place when the number is multiplied by 10.

Linda bought 3 notebooks at $120 each or $3.60 in total. The magazine and water together cost $3.20. So the total of $3.60 + $3.20 is $6.80.

As a refresher, the first place to the left of the decimal point is "1" or single digits, the second place to the left of the decimal point is "10's" so the question asks you to round (down) to the nearest 10. So 32 would become 30.

The decimal .6 is the same as the fraction 6/10. This fraction can be reduced to 3/5 by dividing the numerator and denominator by 2.

Whenever it gets complicated, look at the answers and see if you can find it. If you tried "5" the answer would have been 5 x 13 which is 65, which is too low. Then try the next higher number to see if that solves the problem.

To find out the height of each floor divide 4 into 29 to get 7.25, so the whole number would be between 7 feet and 8 feet.

Do you recall how to factor? You keep dividing the number until you can't divide anymore. The result will be lots of small numbers and a prime number or the smallest non-prime number.

Since 3 x 10 = 30, you know you have to multiply the numerator, 2 by 10 as well to get an equivalent fraction. The same operation is used in the second equivalency equation.

Two tons were taken away by 5 trucks, so each one carried 2/5 of rubble. No pencil or calculator needed!

Since 11 x 4 = 44, we know the answer is 11 plus a remainder of 1. Now divide 4 into 1.0 and get .25. So the answer is the whole number 11 plus the decimal .25 or 11.25.

The decimal .48 can be expressed as 48/100. Once simplified by dividing by 4, the fraction becomes 12/25.