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...

Fill in the Blank

Drew went to the store and bought a scrunchie for $3.99, gum for $1.29, and a hair brush for $6.75. Not including sales tax, estimate how much Drew spent at the store.

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.

Fill in the Blank

Chase buys a taco for $1.79 and a milk for $1.29. About how much money does he spend?

Fill in the Blank

James and his cousin were fishing at the lake. They caught two largemouth bass. One fish weighed 55.27 ounces and the other fish weighed 32.86 ounces. To the nearest whole number, approximately how much did the fish weigh all together?

Fill in the Blank

Tommy is bicycling on a trail. He bikes for 12.45 miles and takes a break. Then he bikes for 10.7 miles. Approximately how many miles has Tommy biked in all?

(round to the nearest whole number)

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