# Question c7216

Nov 3, 2017

$21.4 + 15 + 17.17 + 4.003 = 58$

#### Explanation:

When dealing with addition or subtraction, you need to keep track of the measurements that have the smallest number of decimal places because the result of the operation must be rounded to the same number of decimal places as the value with the smallest number of decimal places.

• $21.4 \textcolor{w h i t e}{1} \text{ } \to$ one decimal place, $4$
• $15 \textcolor{w h i t e}{.11} \text{ } \to$ no decimal place
• $17.17 \text{ } \to$ two decimal places
• $4.003 \text{ } \to$ three decimal places

This means that when you add these measurements, the result cannot have any decimal places. This is the case because your measurements include a value that has no decimal places.

$21.4 + 15 + 17.17 + 4.003 = 57.573$
$57.573 \approx 58$
Keep in mind that you need to round up because the first digit that follows the decimal point, i.e. $5$, is greater than or equal to $5$.
"digit " {(>= 5 implies "round up"), (< 5 implies "round down") :}#