1. Find two factors that multiply to each of: 48 72 60
January 11, Math 102
OBJECTIVE: Students will be able to use estimation to justify the reasonableness of answers
AIM: How do we estimate?
STANDARDS: 7.N.19
PRIOR KNOWLEDGE: Round the following to the nearest underlined digit: ,
Find two factors that multiply to each of:

2. Mini Lesson:
An estimate is a calculation that is reasonably close to an exact answer
What are some of the ways we estimate in daily life?
In math, we can use estimation to see if our answer makes sense:
Example
Darryl weighs pounds. Alicia weighs pounds. About how much more does Darryl weigh than Alicia?

3. Step 1 Round Darryl’s weight to the nearest whole pound
Step 2 Round Alicia’s weight to the nearest whole pound
Step 3 Subtract Alicia’s weight from Darryl’s rounded
weight 179 pounds – 123 pounds = 56 pounds

4. Example
Keisha has 51 brownies to divide among 13 friends. About how many brownies will each friend get?
Strategy: Find compatible numbers – numbers that are easy to divide
Step 1 Find compatible numbers that are close
to 51 and 13 Try 48 and 12
Step 2 Divide the compatible numbers
A reasonable estimate of the number of brownies each friend received is 4