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