Rounding Math Example 2

Solution

1. 1
   Recall: significant figures are counted from the first non-zero digit; leading zeros do not count.
2. 2
   For $\pi$ to $4$ significant figures: the significant digits are $3, 1, 4, 1$; the next digit is $5$, so round up the last kept digit: $3.142$.
3. 3
   For $0.0038472$ to $3$ significant figures: leading zeros are not significant. The significant digits are $3, 8, 4$; the next digit is $7 \geq 5$, so round up the $4$ to $5$: $0.00385$.