Let’s solve each part step by step. We’re looking for the
Greatest Common Factor (GCF) — that means the biggest number that divides both numbers in each pair without leaving a remainder.
We’ll list all factors of each number, find the common ones, and pick the largest.
---
a) 208 and 300
Factors of 208:
1, 2, 4, 8, 13, 16, 26, 52, 104, 208
Factors of 300:
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 25, 30, 50, 60, 75, 100, 150, 300
Common factors: 1, 2, 4 → Biggest is
4
✔ GCF = 4
---
b) 357 and 273
Factors of 357:
1, 3, 7, 17, 21, 51, 119, 357
Factors of 273:
1, 3, 7, 13, 21, 39, 91, 273
Common factors: 1, 3, 7, 21 → Biggest is
21
✔ GCF = 21
---
c) 284 and 224
Factors of 284:
1, 2, 4, 71, 142, 284
Factors of 224:
1, 2, 4, 7, 8, 14, 16, 28, 32, 56, 112, 224
Common factors: 1, 2, 4 → Biggest is
4
✔ GCF = 4
---
d) 308 and 244
Factors of 308:
1, 2, 4, 7, 11, 14, 22, 28, 44, 77, 154, 308
Factors of 244:
1, 2, 4, 61, 122, 244
Common factors: 1, 2, 4 → Biggest is
4
✔ GCF = 4
---
e) 396 and 279
Factors of 396:
1, 2, 3, 4, 6, 9, 11, 12, 18, 22, 33, 36, 44, 66, 99, 132, 198, 396
Factors of 279:
1, 3, 9, 31, 93, 279
Common factors: 1, 3, 9 → Biggest is
9
✔ GCF = 9
---
Final Answer:
a) 4
b) 21
c) 4
d) 4
e) 9
Parent Tip: Review the logic above to help your child master the concept of greatest common factor worksheet 3 digits.
