Question

To multiply a number by 99, Sofia likes to multiply by 100 and then subtract 1 group of the factor. Write an expression with parentheses to show how Sofia would solve 8 × 99.

a) (8 × 100) - 1
b) (8 - 1) × 100
c) (8 × 99) + 1
d) (8 ÷ 100) - 1

Answer 1

The correct expression to show Sofia's method for 8 × 99 is (8 × 100) - 8, which is not provided in the options. The closest correct choice, which reflects the methodology correctly, is not explicitly listed.

Step-by-step explanation:

To write an expression that shows how to multiply a number by 99 using Sofia's method of first multiplying by 100 and then subtracting one group of the factor. To solve 8 × 99 using Sofia's method, the correct expression would be (8 × 100) - 8. This means we multiply 8 by 100 to get 800 and then subtract one group of 8, which gives us 792. However, looking at the provided options, the closest correct choice is (8 × 100) - (8 × 1), which is not listed explicitly. Therefore, while the correct method is delineated, the options given do not accurately reflect the needed calculation.

It is important to note that option a) '(8 × 100) - 1' lacks the correct second term, which should be '8', not '1'.