Question

The sum of three numbers 1.5, 3.2 and 8.5 is to be calculated using the easiest approach possible.

The easiest approach is .

• A. (1.5 + 8.5) + 3.2
• B. (1.5 + 3.2) + 8.5
• C. (8.5 + 3.2) + 1.5

Answer 1

The correct option is A (1.5 + 8.5) + 3.2

The decimals in the given calculation can be broken down as:
1.5 = 1 + 0.5
3.2 = 3 + 0.2
8.5 = 8 + 0.5

Hence, the sum of 1.5 + 3.2 + 8.5 can be expressed as:
1.5 + 3.2 + 8.5 = 1 + 0.5 + 3 + 0.2
+ 8 + 0.5

Now, calculating the result of 0.5 + 0.5 through place value table, we get:


So, 0.5 + 0.5 = 1.0

Hence, grouping the two decimals with the number 5 in their tenths place together make the calculation more simpler.

∴ Using the associative property, the best approach to calculate 1.5 + 3.2 + 8.5 can be expressed as (1.5 + 8.5) + 3.2