Square The Number If You Know Square Of Previous Number

This method is to find square of the number if you know square of the previous number.

You can find answers in three simple steps.

Step 1: Find square of the previous number which is known.

Step 2: Multiply the number being squared by 2 and subtract 1.

Step 3: Add Step 1 and Step 2

Let’s take some examples.

Find square of 31

Step 1: Find square of previous number (30) which is known.

                30² = 900

Step 2: Multiply the number being squared (31) by 2 and subtract 1.

                (31 × 2) – 1 = 62 – 1 = 61

Step 3: Add Step 1 and Step 2

                900 + 61 = 961

Find square of 26

Step 1: Find square of previous number (25) which is known.

                25² = 625

Step 2: Multiply the number being squared (31) by 2 and subtract 1.

                (26 × 2) – 1 = 52 – 1 = 51

Step 3: Add Step 1 and Step 2

                625 + 51 = 676

Find square of 81

Step 1: Find square of previous number (80) which is known.

                80² = 6400

Step 2: Multiply the number being squared (31) by 2 and subtract 1.

                (81 × 2) – 1 =162 – 1 = 161

Step 3: Add Step 1 and Step 2

                6400 + 161 = 6561