Adding A Group
Use the helper fact 2 x 4 to solve 3 x 4
12
8 + 4 = 12
Use the helper fact 5 x 3 to solve 4 x 3
12
15 - 3 = 12
46 - 23 = ?
23
There are 4 tables in the classroom. Each table has 5 students sitting at it. How many students are sitting at the tables altogether?
20 students
4 x 5 = 20
Solve 34 + 28. First estimate by rounding each number to the nearest ten. Then find the exact answer.
30 + 30 = 60
62
Use the helper fact 5 x 3 to solve 6 x 3
18
15 + 3 = 18
Use the helper fact 5 x 4 to solve 4 x 4
16
20 - 4 = 16
72 - 38 = ?
34
The library had 85 books on a shelf. Students checked out 37 books. How many books are left?
48 books
85 - 37 = 48
Solve 246 + 378. First estimate by rounding each number to the nearest hundred. Then find the exact answer.
200 + 400 = 600
624
Use the helper fact 5 x 6 to solve 6 x 6
36
30 + 6 = 36
Use the helper fact 10 x 5 to solve 9 x 5
45
50 - 5 = 45
154 - 76 = ?
78
Ms. Lawler has 36 stickers to share equally among 4 students. How many stickers will each student receive?
9 stickers.
36 ÷ 4 = 9
Draw an array for 10 x 3. Then using the turn-around rule, draw another array and the correct number model.
3 x 10 = 30
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Use the helper fact 5 x 4 to solve 7 x 4. Show how you add two groups.
28
20 + 4 + 4 =28
Use the helper fact 10 x 4 to solve 8 x 4. Show how you subtract two groups.
32
40 - 4 - 4 = 32
623 - 248 = ?
375
A school ordered 6 boxes of pencils. Each box has 5 pencils. The teacher then bought 12 more pencils. How many pencils does the teacher have altogether?
42 pencils
6 x 5 = 30
30 + 12 = 42
Which is easier to solve? 5 groups of 8 or 8 groups of 5? Explain why and solve the problem.
5 x 8 = 40 and 8 x 5 = 40
Counting by 8's five times or counting by 5s eight times
Use the helper fact 5 x 8 to solve 8 x 8. Show how you add the groups.
64
40 + 8 + 8 + 8 = 64
Use the helper fact 10 x 6 to solve 7 x 6. Show how you subtract the groups.
42
60 - 6 - 6 - 6 = 42
1,043 - 587 = ?
456
The third grade is going on a field trip. There are 48 students going. Each bus can hold 10 students. How many buses are needed to take all the students? If each bus costs $25, how much will the school spend altogether?
$125
48 ÷ 10 -> 4 R 8 (Need 5 buses)
5 x 25 = 125
There are four multiplication facts. Which fact is a multiplication sqaure? Explain how you know.
3 x 4
5 x 6
7 x 7
2 x 8
7 x 7 because both factors are the same