Mental Math
Rounding Whole Numbers and Decimals
Addition of Decimals
Problem Solving
Subtraction of Decimals
100
Use mental math to add 2.1+0.9+1.2
4.2
100
Round to the nearest ten: 17
20
100
Find the sum: 3.28+6.09
9.37
100
Nate has a $5 bill and a $10 bill. He spends $2.50 on a smoothie and $2 for a muffin. How much money does he have left?
$10.50
100

Rose needs 22 hamburgers for a party. She has made 12 hamburgers so far. How many more does Rose need to make? 

10 more hamburgers

200

Use mental math to subtract 8.6-4.9

3.7

200
Round to the nearest ten thousand 427,468
430,000
200
Find the sum: $44.00+$91.46
$135.46
200
Lonny planted 15 roses, 12 geraniums and 6 daises. His dog digs up 4 roses and 2 daisies. How many flowers are left?
27 flowers
200
Find the difference: 7.21-6.1
1.11
300

 subtract 4.25-3.08

1.17

300
Round to the nearest whole number: 643.82
644
300

Juan adds 3.8+4.6 and gets a sum of 84. Is his answer correct? How do you know

No he is not correct because 84 is not close to the estimated answer of 4+5. He forgot to add the decimal point, so the sum should be 8.4

300
Elias saved $30 in July, $21 in August and $50 in September. He spent $18 on movies and $26 on gas. How much money does Elias have left?
$57
300
Find the difference: $4.08-$2.12
$1.96
400

 add $3.47+$4.35

$7.82

400
Round to the nearest hundredth: 0.757
0.76
400
What is the sum of 45.09+2.005
47.095
400

A mason needs 22 bricks to make a stoop. So far, he has carried 15 to the site. How many more bricks must he carry?.

7 bricks

400
The pyramid measured 143.5 meters high. The other pyramid measures 65.5 meters high. What is the difference in the heights of the two pyramids?
78 meters
500

On 3 different days at her job, Anne earned $27.50, $33.75 and $49.25. How much money did Anne earn total?

$110.50

500
The world's largest blanket measures 4.26 meters around. Round 4.26 to the nearest ones place and to the nearest tenths place.
4 4.3
500
A balloon mural of the Chicago skyline measures 17.6m on one side and 26.21m on the other two sides. What is the perimeter of the mural?
87.62m
500
Dayana picked apples for 2 hours. She picked 28 apples in the first hour and at the end of 2 hours she had 49 apples. How many apples did she pick during the second hour?
21 apples
500
An average person's leg bone measures 19.88 inches and the lower leg bone measures 16.94 inches. How much longer is the upper leg bone then the lower leg bone?
2.94 inches
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