Determine the approximate value that should replace the question mark (?) in the following expression. (Note: You are expected to estimate rather than compute the precise value).

$59.77\%\text{of}880+79.9\%\text{of}591=?$

To find the approximate value of the expression, we can round each percentage and number to their nearest convenient values for easy calculation.
The given expression is:

$59.77\%\text{ of }880+79.9\%\text{ of }591=?$

Step 1: Round the values to convenient approximations
• $59.77\%$ is approximately $60\%$
• $79.9\%$ is approximately $80\%$
• $591$ is approximately $590$ (or $600$)

Step 2: Calculate each part of the expression
First part: $60\%\text{ of }880$

$60\%\text{ of }880=\frac{60}{100}\times 880=6\times 88=528$

Second part: $80\%\text{ of }591$ (using $590$)

$80\%\text{ of }590=\frac{80}{100}\times 590=8\times 59=472$

Step 3: Add the results together

$?\approx 528+472=1000$

Thus, the approximate value that should replace the question mark is 1000.