Using rules of significant figures, the product 2.5 × 1.25 should be reported as:

Solution

Physics sir · 3 steps

In a product, the answer can only be as precise as the least precise number you multiplied.

1. Count significant figures. 2.5 has 2 significant figures. 1.25 has 3 significant figures.
2. Rule for products. When you multiply or divide, the result keeps as many significant figures as the factor with the fewest. Here that is 2.5, so the answer gets 2 significant figures.

   2.5 × 1.25 = 3.125 → 3.1

3. So. Rounding 3.125 to 2 significant figures gives 3.1, option (c).

The idea to keep. For multiplication and division, count significant figures, not decimal places. The factor with the fewest significant figures decides how many the answer keeps.

Answer from the NTA final answer key. Solution by PrepWiser.