Correct 0.002473 to 3 significant figure

Analyze the question: We need to round 0.002473 to 3 significant figures.

Concept: Significant figures start counting from the first non-zero digit. Leading zeros (the zeros before the first non-zero digit) are only placeholders and do not count.

Solution:

1. Write the number: 0.002473
2. Leading zeros: 0.00 are not significant.
3. The first significant digit is 2, then 4, then 7, then 3. • 1st s.f. = 2 • 2nd s.f. = 4 • 3rd s.f. = 7
4. Look at the next digit (the 4th s.f.), which is 3. Since 3 is less than 5, we round down, so the 7 stays the same.

So 0.002473 ≈ 0.00247 (3 s.f.)

Check against the options:

• A. 0.002 is 1 s.f.
• B. 0.0024 is 2 s.f. (and wrongly rounded)
• C. 0.00247 is 3 s.f. ✔
• D. 0.0025 is 2 s.f. (rounded up)

Tip: Always begin counting significant figures from the first non-zero digit. Then check the digit right after your cut-off point: 5 or more rounds up, and 4 or less leaves the digit unchanged.