Reporting Appropriate Precision

Calculate $4.2\times 3.71$, and report the answer to appropriate precision.

• 1Raw calculator answer: $4.2\times 3.71=15.582$
• 2$4.2$ has $2$ significant figures — the least precise input
• 3Round the answer to $2$ significant figures

Answer: ≈ $16$

Add $12.5$ cm ($1$ decimal place) and $3.42$ cm ($2$ decimal places), and report to appropriate precision.

• 1Raw sum: $12.5+3.42=15.92$
• 2For addition, match the fewest decimal places used (not significant figures): $12.5$ has $1$ decimal place
• 3Round the answer to $1$ decimal place

Answer: $15.9$ cm