Subtraction Meanings
Using Mental Math to Add
Round to the nearest 100
Estimating Sums
Estimating Differences
100
Joan had 12 pies to sell. After she sold some of the pies, she had 4 pies left. How many pies had Joan sold?
What is 8 pies
100
35+26=
What is 61
100
752
What is 800
100
Estimate to the nearest 100 114+58=
What is 100+100= 200
100
Estimate to the nearest ten 88-32=
What is 90-30=60
200
The Jet Propulsion Lab had 9 missions between 2003 and 2006. Two of these missions were to study comets. How many of these missions did not study comets?
What is 7 missions
200
50+42=
What is 92
200
888
What is 900
200
Estimate to the nearest ten 75+72=
What is 80+70=150
200
Estimate to the nearest ten 149-95=
What is 150-100=50
300
Kevin has 17 spelling words to learn this week. He already knows how to spell 9 of the words. How many words does he still need to learn?
What is 8 words
300
63+12=
What is 75
300
207
What is 200
300
Estimate to the nearest hundred 462+251=
What is 500+300=800
300
Estimate to the nearest ten 361-117=
What is 360-120=240
400
A pole holding a state flag is 10 feet tall. The height of the flag is 4 feet. How many feet taller is the pole than the flag?
What is 10-4=6; 6 feet taller
400
65+15=
What is 80
400
732
What is 700
400
Estimate to the nearest hundred 539+399=
What is 500+400=900
400
Estimate to the nearest hundred 186-75=
What is 200-100=100
500
Arizona has 15 counties. Connecticut has 8 counties. How many more counties does Arizona have than Connecticut?
What is 15-8=7; 7 more counties
500
62+34=
What is 96
500
998
What is 1,000
500
Estimate to the nearest hundred 403+179=
What is 400+200=600
500
Estimate to the nearest hundred 704-369=
What is 700-400=300
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