Adding, Subtracting, and Estimating
Round 248 to the nearest hundred, then subtract 100.
200 − 100 = 100
What is (6 × 7)+12?
42 + 12 = 54
write a division problem using 64 divided by 8, then solve it.
answers depend!
A classroom has 4 shelves with 15 books on each shelf. The teacher gives away 20 books. How many books are left?
60-20 = 40
40 books
A baker makes 5 trays of muffins with 8 muffins on each tray. He sells 12 muffins. How many muffins are left?
40-12 = 28 muffins are left
Add 376 + 489, then round the sum to the nearest ten.
865 → 870
9 x 8 = 72
72-15 = 57
57 crayons left
There are 36 students. They form teams of 6. Each team earns 8 points. How many points are earned total?
6 teams x 8 points = 48 points
Liam buys 3 packs of markers with 12 markers in each pack. He gives 14 markers to friends. How many markers does he have left?
36-14 = 22
22 markers
A zoo has 7 cages with 6 animals in each cage. Three animals are moved to another zoo. How many animals remain?
7x6=42
42-3 = 39 animals are left
Samantha has 246 marbles. She buys 137 more and gives 85 to her friend.
How many marbles does she have now?
246 + 137 = 383
383 − 85 = 298
298 marbles
A library has 5 shelves with 12 books on each shelf. They buy 24 more books.
How many books are there now?
5 x 12= 60
60+24=84
84 books
Divide 63 by 7. Then subtract 3.
63÷7= 9
9-3 = 6
A farmer has 8 rows of corn with 9 plants in each row. He removes 18 plants. How many plants remain?
72-18 = 54 plants
There are 48 crayons shared equally among 6 students. Each student gives away 2 crayons. How many crayons do they have total now?
48 ÷ 6 = 8
8-2 = 6
6 x 6 = 36
36 crayons
A store had 482 pencils. They sold 239 pencils on Monday and 178 pencils on Tuesday.
About how many pencils are left? (Round to the nearest ten)
239+178 = 417
482-417 = 65
65→ rounded to nearest ten → 70
What is
(6 x 8) added to (7 x 7)?
6 x 8 = 48
7 x 7 = 49
48 + 49= 97
Divide 72 by 8. Then add 6.
72 ÷ 8 = 9
9+6 = 15
A class has 24 students. They are put into 6 equal groups. Each group earns 5 points.
What is the total points earned?
24 ÷ 6 = 4; 4 × 5 = 20
20 points
A school buys 8 boxes of pencils. Each box has 12 pencils. They give 15 pencils to each of 3 classes. How many pencils are left?
8 x 12 = 96
15 x 3 = 45
96-45= 51 pencils
A library has 765 books. They buy 248 more books and give away 136 books to another school.
Estimate how many books the library has now.
Hint: (Round to the nearest hundred before calculating)
248 --> 200
800+200 = 1,000
136--> 100
1,000-100 = 900
900 books
A baker makes 6 trays of cookies with 12 cookies on each tray. He sells half of the cookies.
How many are left?
72 ÷ 2 = 36
36 cookies
There are 48 crayons. They are shared equally among 8 students. Each student uses 3 crayons.
How many crayons are left?
48 ÷ 8 = 6; 6 − 3 = 3; 3 × 8 = 24
Maya bought 132 erasers for her class. She gave 11 friends the same number of erasers and did not keep any for herself. Later, she collected the erasers back and then shared them equally among her 11 friends and herself.
What is the difference in the number of erasers each friend received the second time compared to the first time?
Explain your thinking.
132 divided by 11 = 12
then 132 divided by 12 11
12-11 = 1
The difference between the number of erasers each friend received the second time compared to the first is 1.
A store packs 6 boxes with 18 items in each box. Then they repack all the items into groups of 9. How many groups are there?
6 x 18 (6 x 10 + 6 x 8) = 108
108÷ 9 = 12
12 groups