Estimating Sums and Differences
By Mr. Bales
Objective
By the end of the lesson, you will be able to estimate sum and differences of numbers.
Standard 4NS3.1 - Demonstrate an understanding of, and the ability to use, standard algorithms for addition and subtraction of multidigit numbers.
Introduce
Look at this number: 2,362
What is this number rounded to the nearest hundred?
Don’t remember – let’s listen to the Rounding Rap
Let’s play “Eliminator” but we’ll round this time
Teach In my left pocket, I have my
entire paycheck - $1.29.
In my right pocket, I have $0.74.
I want to know about how much money I have. What could I do to estimate about how much money I have?
What could $1.29 be rounded to?
What could $0.79 be rounded to?
About how much money is $1.29 + $0.79?
Let’s Watch Mr. Hardesty!!
Mr. Hardesty
Time for Robo Works!!
Robo Works!!
Bales Bucks
Estimate. Round to the place value shown.
312 + 27; tens
1,561 + 305; hundreds
$21.75 + $73.14; tens
383 – 122; hundreds
$74.50 - $52.74; tens
37,215 – 6,792; thousands
$20,425 + $47,236; thousands
Assignment
Page 60 - #’s 9 – 20
Get them all correct – 2 Bales Bucks!!