Round off to 3 significant figure.
0.0003125

Explanation

To round off the number 0.0003125 to three significant figures, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Significant Figures**:
The number 0.0003125 has significant figures starting from the first non-zero digit. In this case, the first non-zero digit is '3'. The significant figures are '3', '1', and '2'.

2. **Count the Significant Figures**:
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