What is Mental Math?

Imagine this: A group of third graders is shopping at a pretend grocery store during math class. One child picks up a carton of milk for $3 and a loaf of bread for $2 and quickly announces, “That’s $5!” without reaching for a pencil or calculator. Moments like these show the power of mental math — the ability to solve math problems in your head.

If you’re a parent, teacher, or tutor working with K-5 students, helping kids develop this skill is one of the most effective ways to strengthen their math abilities and boost their confidence.

In this article, we’ll explore what mental math is, its basic principles, and its incredible benefits. Finally, we’ll learn some strategies to help kids improve their mental math skills, so they can approach numbers with ease and enthusiasm.

What is Mental Math?

Mental math is the ability to solve math problems in your head without using tools like paper, a calculator, or a pencil. It’s a quick and practical way to work with numbers, which helps kids build a strong foundation in math.

In K-5 classrooms, mental math might look like this:

• A kindergartener uses their fingers to quickly figure out what 3 + 2 equals.
• A second grader mentally doubles 6 to find out how many apples two baskets hold.
• A fifth grader quickly calculates 50% off a $10 item during a class activity.

These everyday examples show how kids can solve problems on the spot.

Basic Principles of Mental Math

These basic principles of mental math cover simple techniques that help kids solve math problems quickly in their heads. Here are some that are commonly used with K-5 students:

Breaking Numbers Apart (Decomposition)

Kids learn to break numbers into smaller, easier parts. For example, to solve 23 + 15, they might break it into (20 + 10) + (3 + 5) = 38.

Using Number Patterns

Recognizing number patterns like doubles (4 + 4 = 8) or making tens (7 + 3 = 10), helps kids solve problems faster.

Using Multiplication as Repeated Addition

This mental math trick helps kids understand the concept of multiplication by connecting it to something they already know — adding numbers repeatedly.

For example, 6 × 4 can be calculated as 4 + 4 + 4 + 4 + 4 + 4 = 24

Similarly, 5 × 2 is adding 2 five times: 2 + 2 + 2 + 2 + 2 = 10

Using Inverse Operations

Transform problems into questions that are easier to solve using inverse operations.

For instance, to solve x + 2 = 9, think of it as "What number plus 2 equals 9?" which leads to the inverse operation: 9 − 2 = 7

Skip Counting

This is useful for addition, subtraction, or multiplication. For example, skip counting by 5s (5, 10, 15, 20…) makes solving problems like 4 × 5 easier.

Crossing out common digits

When adding multiple numbers, you can simplify the calculation by grouping similar place values first. For example, in 27 + 38 + 43:

1. Focus on the tens place: Add 20 + 30 + 40 = 90
2. Then, add the ones place: 7 + 8 + 3 = 18
3. Finally, combine the results: 90 +18 = 108

By breaking the problem into smaller, more manageable parts, kids can focus on one step at a time, which makes mental math easier and faster.

Commutative Property

This can be considered a mental math trick, especially for younger children, as it simplifies calculations and builds number flexibility.

Here, they’ll understand that the order of addition (or multiplication) doesn’t affect the result, so kids can rearrange numbers in a way that makes solving problems easier.

For example: To solve 8 + 3, a child might reverse it to 3 8, which feels more natural to them if they are confident adding 8 to 3.

Similarly, 2 × 6 can be flipped to 6 × 2, which may be simpler to visualize as "two groups of six" or "six groups of two."

Benefits of Mental Math for Kids

One of the biggest benefits of mental math is that it improves number sense — the ability to understand and work with numbers easily. As they practice, kids learn how numbers connect to each other and how to break them into smaller parts or combine them.

Another key benefit is how mental math builds focus and memory. When solving problems in their heads, kids must keep track of multiple steps without writing them down. This practice makes their memory and concentration stronger, which is useful not just in math but in other subjects too.

Lastly, mental math lays the groundwork for advanced math concepts. Skills like breaking numbers apart, recognizing patterns, and using shortcuts help kids tackle more challenging topics such as fractions, algebra, and geometry later on.

Tips to Help Kids Improve Their Mental Math

How can you help your child become more confident in mental math? It’s all about mastering the basics, practicing regularly, and finding fun ways to make math engaging. Let’s look at some practical advice below:

Master the basics first

Before tackling more complex problems, ensure your child has a solid understanding of basic arithmetic — addition, subtraction, multiplication, and division. A strong grasp of these concepts lays the foundation for mental math.

Practice consistently

Mental math improves with regular practice. Like any skill, the more you practice, the better you get. Set aside a few minutes each day for simple math problems, whether it’s through worksheets, flashcards, or verbal practice.

Take advantage of everyday situations to strengthen these skills — whether they’re adding up groceries, splitting snacks with friends, or figuring out time. Consistency helps build speed and confidence over time.

Incorporate math games

Math games are fun and keep kids engaged while improving their skills. Board games, card games, or even apps focused on math can make learning feel like play!

For example, "Skip Counting" is a great mental math trick that can be practiced through games like "Skip Counting Bingo". In this game, kids practice counting by 2s, 5s, 10s, and other numbers to mark off spaces on their bingo cards, which reinforces their skip counting skills.

Summary

Remember, mastering these skills takes time and consistent practice. Help your child start small, focus on accuracy first, and gradually increase the complexity of problems as they get more comfortable. It’s important to emphasize getting the right answers before trying to solve problems faster.

Check out this article to discover more mental math tricks!