If your problem is 687 - 239, it makes sense to me to do it this way:
700 = 200 = 500
Use front-end estimation to find the value of the expression. I do not understand (without adjustment)
687 - 239 (without adjustment)
is this right?
600 + 200= 800 + 126=926
5 answers
Correction:
700 - 200 = 500
700 - 200 = 500
Right it was subtraction. So what does "without adjustment" mean?
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
This site may explain it.
http://mathforum.org/library/drmath/view/65415.html
Thank you