Use front-end estimation to find the value of the expression. I do not understand (without adjustment)

Question

687 - 239 (without adjustment)

is this right?

600 + 200= 800 + 126=926

Answer 1

If your problem is 687 - 239, it makes sense to me to do it this way:

700 = 200 = 500

Answer 2

Correction:

700 - 200 = 500

Answer 3

Right it was subtraction. So what does "without adjustment" mean?

Answer 4

I'm not a math teacher -- but I assume you don't need to adjust for the small differences between your estimated numbers and the actual numbers.

This site may explain it.

http://mathforum.org/library/drmath/view/65415.html

Answer 5

Thank you