What is mental math?

Mental math is a group of skills that allow people to do math “in their head” without using pencil and paper or a calculator. One of these skills is remembering math facts, like 8 × 5 = 40. Other skills include rounding numbers and estimating calculations.

Mental math is useful in everyday life to answer questions like:

• What is the sale price for this item?

• Do I have enough cash to buy everything in my cart?

• Am I getting the correct amount of change from the cashier?

• When should I leave in order to arrive on time?

Mental math can also help kids understand math concepts better. Using and practicing mental math regularly helps kids improve their number sense.

For example, which is a better deal? Buying a box of 10 packs of gum for $18.00 or buying individual packs for $2.50 each? Use mental math to quickly estimate that the 10-pack must cost less than $2.00 per pack because 10 × 2 = 20. This is a better deal than the second option where each pack costs more than $2.00.

Mental math is useful in other ways too. It keeps math facts from getting rusty. It can also help get to the answer faster.

For example, what is 47 + 65? It’s easier to do this in your head if you break the numbers down into their digits’ values: 40 + 60 = 100 and 7 + 5 = 12. Add those two totals and you get the answer of 112.

Doing mental math requires strong memory skills. Math facts and other number concepts have to be retrieved from long-term memory. Our brains also use a skill called working memory to keep track of the steps needed to solve a particular math problem.

When kids struggle with mental math, it doesn’t mean they’re not smart. Kids develop math skills at their own pace. Difficulty with mental math could be a matter of needing more time and practice to “catch up.”

Trouble with mental math could also be a sign that your child needs more support to get better at math. Learn about math challenges in kids and ways to help.