Estimating and Adding

Sums and Differences

Example no. 1

Example no. 2

Example no. 3

Example no. 4

Example no. 3

Multiple Choice

655 +111 =    𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒: 𝑅𝑜𝑢𝑛𝑑 𝑡𝑜 𝑡ℎ𝑒 𝑛𝑒𝑎𝑟𝑒𝑠𝑡 ℎ𝑢𝑛𝑑𝑟𝑒𝑑 and then add.  

• 770
• 800
• 680
• 760

Multiple Choice

Estimate the sum of 120+190 by rounding to the nearest hundreds

• 300
• 250
• 350
• 200

Multiple Choice

Estimate the sum of 52+59 by rounding to the nearest tens

• 110
• 150
• 120
• 100

Multiple Choice

Estimate to the ten thousands place and then subtract
47,623 - 12,385 =

• 35,238
• 40

• 40,000

• 30,000

Estimation

Estimation is when you use rounding to get an approximate answer.

For example: Mrs. Azzarello bought a sandwich for $5.99, a soda for $1.89, and a bag of chips for $3.25. About how much did she spend?

If you round each amount to the nearest dollar, you can add much easier and quicker...

$6 + $2 + $3 = $11

Mrs. Azzarello spent about $11

Estimation

Typically you round decimals to the nearest whole number when estimating... unless told otherwise!

Here are some for you to try...

Estimation

When reading a story problem...you will not always see the word "estimate". Other words that mean estimate include "about" or "approximately". Look for these key words in the next few problems.

Estimate Sums

• First, round each addend to an easier number

• Then, add

Multiple Choice

Estimate the sum of 327+431 by rounding to the nearest hundreds

• 700
• 600
• 900
• 800

Multiple Choice

Estimate the sum of 120+190 by rounding to the nearest hundreds

• 200
• 250
• 350
• 300

Multiple Choice

Estimate the sum of 52+59 by rounding to the nearest tens

• 120
• 150
• 100
• 110

Multiple Choice

Estimate the sum of 37+99 by rounding to the nearest tens

• 140
• 160
• 150
• 130

Estimate differences

• First, round the minuend and subtrahend to make subtraction easier

• Then, subtract

Multiple Choice

Round to the nearest hundred, then estimate:

642 − 137

• 400
• 600
• 500
• 700

Multiple Choice

Estimate the difference to

71-37=

• 23
• 45
• 29
• 30

Multiple Choice

Round to the nearest hundred to estimate 2,252 - 198.

• 2,400
• 2,100
• 2,000
• 2,300

Multiple Choice

Round to the nearest hundred to estimate 5, 384 - 198.

• 5, 200

• 5,210

• 5,000

• 3,000