This document discusses strategies for using mental math to solve whole number expressions. It provides examples of adding, subtracting, and multiplying whole numbers using strategies like rearranging terms, breaking numbers apart, and using compatible numbers. Students are assigned in-class work and homework problems applying these mental math strategies.

1. Math 6:Whole Numbers
Using Mental Math to Add

2. Getting started
 70 + 89 + 30
 What mental strategy did you use to solve the expression?
 572 – 131
 What mental strategy did you use to solve the expression?
 4 x 33
 What mental strategy did you use to solve the expression?
 5 x 18 x 20
 What mental strategy did you use to solve the expression?

3. Connect –Ways to Use Mental Math
 Use mental math to add
 Rearrange and use compatible numbers.
 Compatible numbers are pairs of numbers that are easy to
calculate.
 For example, add 60 + 35 + 40
 You would first add 60 + 40 = 100
 Then add 100+35 = 135.

4. Ways to Use Mental Math
 Use Mental Math to Subtract
 687-464
 When no regrouping is needed, start subtracting from the left.
 Use Mental Math to Multiply
 Rearrange and use compatible numbers.
 4 x 19 x 25
 =(4 x 25) x 19
 =100 x 19
 =1900

5. Ways to Use Mental Math
 Use Mental Math to Multiply: 6 x 27
 Break one of the numbers apart to make numbers that are
simple to work with.
 27 = (20 + 7)
 (6 x 20) = 120
 (6 x 7) = 42
 120 + 42 = 162

6. In class work
 pg. 51 #1-3 a, c, f, and 4, 5, 8

7. Homework
 pg. 22 + 23