10 mental math tricks that actually make life easier

Ever try to split the check, figure out a tip, or calculate a discount in your head—and suddenly realize you’re blanking? 

Mental math can feel like a lost skill in the age of phone calculators. But with just a few easy-to-learn techniques, you can handle everyday math faster and with way more confidence.

These 10 mental math tricks aren’t going to be about memorizing formulas or impressing people at parties. They’re about making life easier. Whether you’re trying to stay on budget, calculate your monthly expenses on the fly, or just keep your brain sharp, these strategies can help.

And if you want a place to practice these skills regularly, the Elevate app has daily math games designed to improve your speed and accuracy over time—without the stress of flashcards.

Let’s get into it.

Mental math trick #1: Round first, then adjust

One of the simplest ways to speed up math in your head is to round to easy numbers, solve, and then adjust the result.

For example:

• 387 + 456 → round to 400 + 460 = 860 → subtract 13 + 4 = 843

The same works for multiplication: 

• 48 × 5 → round to 50 × 5 = 250 → subtract 2 × 5 = 240

This method is especially useful when budgeting or estimating totals while shopping. Even if your final answer isn’t exact, you’ll be close—and it’ll be much faster.

Mental math trick #2: Start from the left

Most of us were taught to add from right to left on paper. But in your head, it’s actually easier to do the opposite. 

Here’s what we mean:

• 576 + 485 →
  
  • Hundreds: 500 + 400 = 900
  • Tens: 70 + 80 = 150
  • Ones: 6 + 5 = 11
  • Total = 1,061

This approach makes it easier to track where you are in the problem. It’s especially helpful when you’re adding a series of numbers or working quickly.

And, if you’re looking to improve your number sense, this is a great place to start.

Mental math trick #3: Multiply by 11 without writing it down

Here’s a trick that feels like magic once you get it down: To multiply any two-digit number by 11, add the digits together and place the result in between. 

For example: 

• 24 × 11 → 2 and 4 → 2 + 4 = 6 → final = 264
• 75 × 11 → 7 + 5 = 12 → carry 1 → 8 (2) 5 = 825
• 248 × 11 → 2 + 4 = 6, 4 + 8 = 12 → carry 1 → 2,728

As you can see, this works with three-digit numbers, though the mental math gets trickier. Still, it’s fast, accurate, and a great way to keep your brain working in patterns.

Mental math trick #4: Use 9 to your advantage

Multiplying by 9 can be quicker than it looks. For single-digit numbers, subtract 1 from the number, and subtract that from 9. So, 9 times 4? Subtract 1 to get 3, then 9 minus 3 equals 6. That gives you 36. 

Let’s break that down again: 

• 9 × 4 → 4 − 1 = 3, 9 − 3 = 6 → 36
• 32 × 9 → 32 × 10 = 320 → 320 − 32 = 288

Also try the 9-times table finger trick or digit-sum check (72 → 7 + 2 = 9).

It’s also worth noticing patterns. Multiples of 9 always add up to 9: 4 + 5 = 9, 6 + 3 = 9, 7 + 2 = 9. These patterns are especially useful when checking your work under pressure, like in a timed test or while estimating costs on the go.

Mental math trick #5: Square numbers that end in 5

Here’s a mental shortcut for squaring any number that ends in 5. Just multiply the base by its next neighbor, then tack on 25 like this:

• 45² → 4 × 5 = 20 → 2025
  
  
• 75² → 7 × 8 = 56 → 5625
  
  
• 115² → 11 × 12 = 132 → 13,225

This trick is rooted in a mathematical formula, but you don’t need to remember it. Just practice a few times, and it’ll start to feel automatic.

Mental math trick #6: Estimate percentages in your head

Calculating percentages is one of the most practical mental math skills, and it’s easier than you think. 

Let’s start with 10%:

• 10% of 340 = 34

Now let’s try 20%:

• 20% of $60 → 10% = 6 → double = $12

Finally, let’s see how this works with 40%:

• 40% off $70 → 10% = 7 → 7 × 4 = $28 → Pay = $42

Even if the numbers aren’t perfect, estimating percentages gets you close enough to make quick decisions—whether you're tipping, shopping, or budgeting. (Pro tip: The Elevate app’s Percentages game is a great way to get faster at this.) 

Mental math trick #7: Use compensation to add and subtract faster

Let’s say you’re adding 68 and 57. Rather than doing it the traditional way, try adjusting the numbers to be easier to work with. 

For example:

• 68 + 57 → (68 + 2) + (57 − 2) = 70 + 55 = 125
  
  
• 1,000 − 556 → 9−5, 9−5, 10−6 → 444

These kinds of tricks help you get to the answer faster—and they reduce the cognitive load, especially when you’re doing multiple calculations in your head.

Mental math trick #8: Double numbers by breaking them apart

Doubling numbers quickly can be useful for budgeting, scheduling, or estimating. 

Let’s say you want to double 183: 

• 183 → double 180 = 360, double 3 = 6 → 366

Next, try doubling 1,481: 

• 1,481 → 2 × 1,500 = 3,000 → subtract 38 = 2,962

With enough practice, it becomes automatic—and surprisingly satisfying—when estimating budgets, expenses, or recurring costs. 

Mental math trick #9: Simplify division in steps

Mental division is all about simplification. 

Here’s a simple and a more complex example:

• 2,500 ÷ 5 → 5,000 ÷ 10 = 500
  
  
• 35,420 ÷ 70 → 35,000 ÷ 70 = 500, 420 ÷ 70 = 6 → 506

When both numbers share a trailing zero, remove it. And when dividing by numbers like 4 or 8, try halving repeatedly. These small tricks add up to big improvements in mental speed.

Mental math trick #10: Picture numbers to remember them

Mental math isn’t just about calculation—it’s also about recall. The more clearly you can picture numbers, the faster you can work with them. 

Here are some techniques to help you do just that: 

• Visualize a number line when adding/subtracting
  
  
• Break large numbers: 324,537 → 324 + 537
  
  
• Use mental tens frames or skywriting techniques
  
  
• Try phonetic memory (721 → “GAB”) for digits

Some people also use techniques like drawing numbers in the air or using a mental tens frame to visualize how close they are to the next round number. If you’re a visual learner, these methods make a big difference.

Want to improve your mental math skills without memorizing flashcards or formulas? 

The Elevate app’s math games are built to help you get faster and more accurate with the skills you use every day—whether that’s doubling, estimating, or just doing quick math under pressure. 

So what are you waiting for? Start training your brain like it matters—because it does, every time you tip, split, or spend.