Final answer:
To estimate the sum of $642.23 and $861.17 to the nearest hundred dollars, round each amount and then add the rounded figures. The rounded amounts are $600 and $900, giving an estimated sum of $1500.
Step-by-step explanation:
To estimate the sum of $642.23 and $861.17 to the nearest hundred dollars, first round each number to the nearest hundred.
- $642.23 rounds down to $600 because $42.23 is less than $50.
- $861.17 rounds up to $900 because $61.17 is more than $50.
Now, add the rounded amounts:
$600 + $900 = $1500
The estimate of the sum of $642.23 and $861.17 to the nearest hundred dollars is therefore $1500.