# Suppose you add a measurement of 7.2 mL to a measurement of 15.37 mL. How many decimal places should the answer have?

##### 1 Answer

The answer must have

#### Explanation:

The thing to remember when dealing with *addition or subtraction* is that the result **must** be rounded to the **same number of decimal places** as the measurement with the *least number* of decimal places.

In your case, you have two measurements, **one decimal place**, and **two decimal places**.

This means that the value you get by *adding* these two measurements must be rounded to **one decimal place**.

So, add the two measurements to get

#"7.2 mL " + " 15.37 mL" = "22.57 mL"#

Now, this number, *tenths place*, i.e. to one decimal place. You will thus have

#22.5color(red)(cancel(color(black)(7))) implies 22.6#

Therefore, adding your two measurements will get you

#color(green)(|bar(ul(color(white)(a/a)color(black)("7.2 mL " + " 15.37 mL" = "22.6 mL")color(white)(a/a)|)))#