Rounding and Mental Math
Estimating
Adding Decimals
Subtracting Decimals
Word Problems
100
Round 10.245 to the nearest whole number.
What is 10
100
19.9 + 17.03
What is 37
100
3.77 + 4.66
What is 8.43
100
9.21 - 1.72
What is 7.49
100
A dollhouse has 15.15 square feet downstairs and 6.25 feet upstairs. What is the best estimate of the total squire footage of the dollhouse? Is this an overestimate or underestimate?
21 and underestimate
200
Round 9.145 to the nearest hundredth
What is 9.15
200
9.32 + 2.95
What is 12
200
125.9 + 6.77
What is 132.67
200
5.7 - 0.623
What is 5.077
200
Jared rode in a bike race and covered 7 kilometers on the first day. The race is 25 kilometers. How much further does he have to ride?
18 kilometers.
300
Use mental math to add 35 + 14 + 16
What is 65
300
3.8 + 4.1 + 3.3
What is 11
300
10.93 + 0.96
What is 11.89
300
81.12 - 37.202
What is 43.918
300
Joe has a $20 bill and a $5 bill. He spends $4.29 for a slice of pizza and $3 for some french fries. How much money does he have left? What are the hidden questions for this problem? What is the answer?
How much money does Joe originally have? How much money does he spend on food? Answer: $17.71
400
Use mental math to add: 24.1 + 1.2 + 8.8
What is 34.1
400
16.98 - 9.29
What is 8
400
1.847 + 0.217
What is 2.064
400
19.006 - 7.5
What is 11.506
400
Parson's Sporting Goods ordered 56 T-shirts in sizes small, medium, and large. If 23 T-shirts are medium and 12 T-shirts are large, how many are small?
21
500
Use mental math: 86-4.9
What is 81.1
500
74.05 + 9.72 + 45.79
What is 130
500
0.789 + 1.649
What is 2.438
500
34.49 - 12.619
What is 21.871
500
Adam has $87.25. His friend Kyle owes him $7.69. How much money will Adam have when Kyle repays him?
$94.94
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