estimating sums and differences

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!!