Round off to 3 significant figures (a) 20.96 and (b) 0.0003125

Explanation

To round off the numbers to three significant figures, we will follow these steps:

### Step 1: Round off 20.96
1. Identify the first three significant figures in the number 20.96. The significant figures are 2, 0, and 9.
2. Look at the digit immediately after the third significant figure (which is 6 in this case).
3. Since 6 is greater than 5, we round up the last significant figure (9) by 1.
4. Therefore, 20.96 rounded to three significant figures becomes 21.0.

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