Andrew was making a science project for school. He worked for 6.6 hours the first week, 2.75 hours the second week, and 4.4 hours the third week.

Question

Andrew used the following mental math strategy to find the total number of hours he worked on his project.

6.6 + 2.75 + 4.4
(6.6 + 4.4 ) + 2.75
11 + 2.75 = 13.75

Answer 1

Andrew's mental math strategy for adding the hours he worked on his science project is correct. He grouped the first and third week's hours together before adding them to the second week's hours. Here's a step-by-step breakdown of his method:

1. Add the hours from the first and third weeks: \[ 6.6 + 4.4 = 11 \]

2. Now, add the result from step 1 to the hours from the second week: \[ 11 + 2.75 = 13.75 \]

Thus, the total number of hours Andrew worked on his science project over the three weeks is 13.75 hours.

His method of grouping the numbers makes it easier to perform the addition, and he correctly calculated the total.