Quick Mental Math Tricks for Students (7 Tricks)

Ever wished you could solve math problems in your head faster? You're not alone! Many students find mental calculation challenging, but with the right tricks up your sleeve, you can become a calculation wizard. Let's dive into some quick and easy mental math tricks that will have you crunching numbers in no time.

Why Mental Math Tricks Matters?

Before we jump in, you might wonder: "Why bother with mental math when I have a calculator?" Good question! Mental math:

• Sharpens your overall math skills
• Saves time on tests and in daily life
• Boosts your confidence with numbers
• Improves your memory and focus

Now, let's get to the good stuff – the mental math tricks!

Addition and Subtraction Tricks

Addition and subtraction can be made easier with various mental math tricks.

The "Make 10" Method

This trick is all about making friendly numbers that are easy to work with.

How it works:

1. When adding, look for numbers that sum to 10.
2. Group these numbers first, then add the rest.

Example: 7 + 6 + 3 = ?

• Spot the 7 and 3 (they make 10)
• Group them: (7 + 3) + 6
• 10 + 6 = 16

Practice: Try these:

1. 8 + 5 + 2 = ?
2. 9 + 7 + 1 = ?

The "99 Trick"

Adding 99 to a number is almost like adding 100, which is super easy!

How it works:

1. Add 100 to the number
2. Subtract 1 from the result

Example: 456 + 99 = ?

• 456 + 100 = 556
• 556 - 1 = 555

Practice:

1. 234 + 99 = ?
2. 578 + 99 = ?

Multiplication Shortcuts (The "11 Rule" & Multiplying by 5)

Multiplication shortcuts as mental math tricks can significantly simplify calculations.

The "11 Rule"

Multiplying by 11 is easier than you think!

How it works (for 2-digit numbers):

1. Separate the digits of the number you're multiplying by 11
2. Add those two digits
3. Place the sum between the original digits

Example: 11 x 42 = ?

• Separate: 4 __ 2
• Add: 4 + 2 = 6
• Place between: 462

Note: If the sum is over 9, carry the 1 to the left digit.

Practice:

1. 11 x 35 = ?
2. 11 x 68 = ?

Multiplying by 5

Here's a quick trick for multiplying any number by 5.

How it works:

1. Divide the number by 2
2. Add a zero at the end

Example: 5 x 18 = ?

• 18 ÷ 2 = 9
• Add 0: 90

Note: If the number is odd, divide, round down, and add a 5 at the end.

Example: 5 x 37 = ?

• 37 ÷ 2 = 18.5 (round down to 18)
• Add 5: 185

Practice:

1. 5 x 24 = ?
2. 5 x 43 = ?

Quick Division Tricks (Dividing by 5)

Another trick of mental math is dividing by 5. This is the reverse of multiplying by 5!

How it works:

1. Multiply the number by 2
2. Move the decimal point one place to the left

Example: 85 ÷ 5 = ?

• 85 x 2 = 170
• Move decimal: 17.0

Practice:

1. 125 ÷ 5 = ?
2. 60 ÷ 5 = ?

Percentage Calculations (Finding 10% Quickly)

How it works: Move the decimal point one place to the left.

Example: 10% of 340 = ?

• Move decimal: 34.0

Practice:

1. 10% of 780 = ?
2. 10% of 1250 = ?

Using 10% to Find Other Percentages

Once you know 10%, you can find other percentages easily.

Examples:

• 5% is half of 10%
• 20% is double 10%
• 25% is 10% + 10% + 5%

Practice: Using 780 from the previous example:

1. What's 5% of 780?
2. What's 20% of 780?
3. What's 25% of 780?

Squaring Numbers Ending in 5

This mental math trick works for any number ending in 5.

How it works:

1. Multiply the tens digit by the next whole number
2. Add 25 to the end of the result

Example: 35² = ?

• Tens digit: 3
• Next whole number: 4
• 3 x 4 = 12
• Add 25: 1225

Practice:

1. 25² = ?
2. 45² = ?

Estimation Techniques (Rounding to Nearest 10)

Sometimes, you don't need an exact answer. Estimation can save you time!

How it works: Round each number to the nearest 10 before calculating.

Example: 178 + 234 = ?

• 178 rounds to 180
• 234 rounds to 230
• 180 + 230 = 410 (close to the actual answer of 412)

Practice: Estimate these:

1. 167 + 292 = ?
2. 543 - 298 = ?

Memory Techniques for Mental Math (Chunking)

Break long numbers into smaller, manageable chunks.

Example: Remember the number 941,873,265 Break it into: 941 - 873 - 265 Visualize or create a story with these chunks.

Practice: Try chunking these numbers:

1. 728,394,516
2. 305,871,942

Conclusion

Mental math doesn't have to be intimidating. With these quick mental math tricks, you can boost your calculation speed and confidence. Remember, practice makes perfect. Try incorporating these techniques into your daily life – at the store, while doing homework, or even when you're just bored!

FAQs

1. How long does it take to get good at mental math?

With regular practice, you can see improvement in just a few weeks. Consistency is key!

2. Can these mental math tricks replace the need for a calculator?

While these mental math tricks are handy, calculators are still important for complex calculations. Use mental math for quick estimates and simpler problems.

3. Are there mental math competitions?

Yes! Many schools and organizations hold mental math competitions. They're a great way to challenge yourself and meet like-minded math enthusiasts.

4. Can mental math help with standardized tests?

Absolutely! Mental math can save you precious time on timed tests, mental arithmetic tests and help you check your work quickly.

5. Is it ever too late to learn mental math tricks?

Not at all! Your brain can learn new skills at any age. Start practicing mental arithmetic today, and you'll be surprised at how quickly you improve.