GCF for 12, 21 and 30
"Greatest Common Factor of 3 Numbers" Calculator
What's the Greatest Common Factor (GCF) of 12, 21 and 30?
Answer
GCF of 12, 21 and 30 is
3
Common factors: 1, 3
3 divides all three: 12 ÷ 3 = 4, 21 ÷ 3 = 7, 30 ÷ 3 = 10 — and 4, 7 and 10 have no factor but 1 common to all of them, so no larger number divides all three.
12 = 22 × 3
21 = 3 × 7
30 = 2 × 3 × 5
| Prime | 12 | 21 | 30 | Lowest power |
|---|---|---|---|---|
| 2 | 22 | — | 2 | — |
| 3 | 3 | 3 | 3 | 3 |
| 5 | — | — | 5 | — |
| 7 | — | 7 | — | — |
— = power 0: the prime is not a factor of this number, so it cannot be in the GCF.
GCF = 3
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See Also
- Least Common Multiple of 3 Numbers - Find the Least Common Multiple (LCM) of three numbers
- Greatest Common Factor - Find the Greatest Common Factor (GCF) of two numbers
- Least Common Multiple - Find the Least Common Multiple (LCM) of two numbers
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