SAMPLE: This is how I would like you to answer Questions #2 and #3. Use ROY G. BIV to show the order in which you do things. For the first question, you will only need to initial my diagram to get credit for Question 1.
Find the value of the expression. Use estimation to check your answer: 2570 + 3145 + 3879
Find the value of the expression. Use estimation to check your answer: 3145 - 2570