Let’s solve this step by step.
We are given pairs of numbers and need to fill in:
-
Multiplication (just multiply the two numbers)
-
GCF (Greatest Common Factor — the largest number that divides both)
-
LCM (Least Common Multiple — the smallest number that both divide into)
Then we check if:
> LCM = Multiplication / GCF ?
This is actually a true math rule! So it should work for all pairs.
---
Let’s go row by row:
Row 1: 6, 7
- Multiplication: 6 × 7 =
42
- GCF: Factors of 6 → 1,2,3,6; Factors of 7 → 1,7 → only common factor is
1
- LCM: Since they’re coprime (GCF=1), LCM = 6×7 =
42
→ Check: 42 / 1 = 42
✔
Row 2: 8, 9
- Multiplication: 8 × 9 =
72
- GCF: 8 → 1,2,4,8; 9 → 1,3,9 → only
1
- LCM: 8×9 =
72 (since GCF=1)
→ 72 / 1 = 72
✔
Row 3: 4, 9
- Multiplication: 4 × 9 =
36
- GCF: 4 → 1,2,4; 9 → 1,3,9 → only
1
- LCM: 4×9 =
36
→ 36 / 1 = 36
✔
Row 4: 5, 7
- Multiplication: 5 × 7 =
35
- GCF: both prime →
1
- LCM: 5×7 =
35
→ 35 / 1 = 35
✔
Row 5: 6, 12
- Multiplication: 6 × 12 =
72
- GCF: factors of 6 → 1,2,3,6; 12 → 1,2,3,4,6,12 → greatest common is
6
- LCM: multiples of 6: 6,12,18...; 12: 12,24... → least common is
12
→ Check: 72 / 6 = 12
✔
Row 6: 4, 16
- Multiplication: 4 × 16 =
64
- GCF: 4 → 1,2,4; 16 → 1,2,4,8,16 → greatest common is
4
- LCM: 16 is multiple of 4 → so LCM =
16
→ 64 / 4 = 16
✔
Row 7: 10, 40
- Multiplication: 10 × 40 =
400
- GCF: 10 → 1,2,5,10; 40 → 1,2,4,5,8,10,20,40 → greatest common is
10
- LCM: 40 is multiple of 10 → LCM =
40
→ 400 / 10 = 40
✔
Row 8: 7, 14
- Multiplication: 7 × 14 =
98
- GCF: 7 → 1,7; 14 → 1,2,7,14 → greatest common is
7
- LCM: 14 is multiple of 7 → LCM =
14
→ 98 / 7 = 14
✔
Row 9: 6, 8
- Multiplication: 6 × 8 =
48
- GCF: 6 → 1,2,3,6; 8 → 1,2,4,8 → greatest common is
2
- LCM: multiples of 6: 6,12,18,24...; 8: 8,16,24... → LCM =
24
→ 48 / 2 = 24
✔
Row 10: 8, 12
- Multiplication: 8 × 12 =
96
- GCF: 8 → 1,2,4,8; 12 → 1,2,3,4,6,12 → greatest common is
4
- LCM: multiples of 8: 8,16,24...; 12: 12,24... → LCM =
24
→ 96 / 4 = 24
✔
Row 11: 10, 15
- Multiplication: 10 × 15 =
150
- GCF: 10 → 1,2,5,10; 15 → 1,3,5,15 → greatest common is
5
- LCM: multiples of 10: 10,20,30...; 15: 15,30... → LCM =
30
→ 150 / 5 = 30
✔
Row 12: 12, 18
- Multiplication: 12 × 18 =
216
- GCF: 12 → 1,2,3,4,6,12; 18 → 1,2,3,6,9,18 → greatest common is
6
- LCM: multiples of 12: 12,24,36...; 18: 18,36... → LCM =
36
→ 216 / 6 = 36
✔
---
Now, let’s fill the table with our answers:
| The numbers | Multiplication | GCF | LCM |
|-------------|----------------|-----|-----|
| 6, 7 | 42 | 1 | 42 |
| 8, 9 | 72 | 1 | 72 |
| 4, 9 | 36 | 1 | 36 |
| 5, 7 | 35 | 1 | 35 |
| 6, 12 | 72 | 6 | 12 |
| 4, 16 | 64 | 4 | 16 |
| 10, 40 | 400 | 10 | 40 |
| 7, 14 | 98 | 7 | 14 |
| 6, 8 | 48 | 2 | 24 |
| 8, 12 | 96 | 4 | 24 |
| 10, 15 | 150 | 5 | 30 |
| 12, 18 | 216 | 6 | 36 |
And yes — for every row,
LCM = Multiplication ÷ GCF holds true.
Final Answer:
The completed table is as above, and yes, it is correct to say:
The LCM = Multiplication / GCF
Parent Tip: Review the logic above to help your child master the concept of gcf and lcm worksheet.