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.

30^{2} = 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.

25^{2} = 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.

80^{2} = 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