Anne's utility bills for three months were $59, $67, and $33. To add the utility bills mentally, Anne thought
"(59+67)+33=59+(67+33)."
yup, always "scan" the number to see how they fit together.
good job
Anne's mental approach to adding the utility bills is using the associative property of addition. The associative property states that the grouping of numbers being added does not affect the sum. In simpler terms, when adding three or more numbers, you can group any two numbers together and then add the third number.
To add the utility bills mentally, Anne grouped the first two bills together and added them first:
(59 + 67)
This resulted in a sum of 126.
Then, Anne added the third bill to the previous sum:
126 + 33
This final step gives the total utility bill amount of 159.
So, according to Anne's mental approach, the sum of Anne's utility bills for three months is $159.
To add the utility bills mentally, Anne can use the associative property of addition, which states that changing the grouping of the numbers being added does not change the sum.
First, she can add 59 and 67 together:
59 + 67 = 126.
Then, she adds the sum to the remaining number:
126 + 33 = 159.
So, the total utility bills for three months is $159.