Question

When Ashley was asked to round 345 to the nearest 100, she rounded 345 to 350 and then rounded 350 to 400. Billie claimed the answer was 300. How would you respond to these students?

Answer 1

Rounding of a number to nearest 100:

To round of a number to be nearest 100, make the number of the last two digits which are < 50 to the lowest 100th value. And the numbers of the last two digits which are > 50 to the next possible hundred.

That is, to the nearest number which is a multiple of 100

For instance,

Consider 427, to round off to nearest 100, 27 is numbered to nesrest hundred, the number is 400 which is the lowest 100.

If number is 488, rounding to nearest 100, 88 is rounded off to the number 500 which is the next possible hundred.

Now,

Given,

Ashley was asked to round 345 to the nearest 100, she rounded 345 to 350

She rounded to the nearest 10, Her answer was wrong.

Later, she rounded 400 which is the next possible hundred, But she need to round off to the lowest possible hundred if the last two digits are < 50.

Then rounding 345 is 300.

Billie caimed the answer was 300

Bille was correct as rounding 345 to nearest 100 is 300