Square Trick: How to Square Numbers Ending in 5

 

Introduction

Squaring numbers ending in 5 becomes very easy once you learn this simple Mental Math trick. Instead of multiplying the number by itself, you can calculate the answer in just a few seconds.

The Trick

For any number ending in 5:

  1. Take the digit(s) before 5.

  2. Multiply that number by its next number.

  3. Write 25 at the end.

Formula:

N5² = N × (N + 1) followed by 25

Example 1

25²

Step 1:

Take 2

Step 2:

2 × 3 = 6

Step 3:

Attach 25

Answer = 625

Example 2

35²

Step 1:

Take 3

Step 2:

3 × 4 = 12

Step 3:

Attach 25

Answer = 1225

Example 3

45²

Step 1:

Take 4

Step 2:

4 × 5 = 20

Step 3:

Attach 25

Answer = 2025

Example 4

65²

Step 1:

Take 6

Step 2:

6 × 7 = 42

Step 3:

Attach 25

Answer = 4225

Example 5

95²

Step 1:

Take 9

Step 2:

9 × 10 = 90

Step 3:

Attach 25

Answer = 9025

Practice Questions

Try these yourself:

  1. 15²

  2. 55²

  3. 75²

  4. 85²

  5. 105²

Answers

  1. 225

  2. 3025

  3. 5625

  4. 7225

  5. 11025

Key Learning

Whenever a number ends in 5, you never need long multiplication. Simply multiply the leading number by its next number and add 25 at the end.

Practice Tip

Memorize this pattern:

  • 15² = 225

  • 25² = 625

  • 35² = 1225

  • 45² = 2025

After a few examples, the trick becomes automatic.

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