GCF and LCM of 20 and 22

The GCF of 20 and 22 is 2. The LCM of 20 and 22 is 220.

Method 1: list the factors (GCF)

Factors of 20: 1, 2, 4, 5, 10, 20.
Factors of 22: 1, 2, 11, 22.
Common factors: 1 and 2. The greatest of these is 2.

Method 2: prime factorization

20 = 2 × 2 × 5
22 = 2 × 11

GCF: multiply the prime factors both numbers share: 2 = 2.

LCM: multiply every prime the maximum number of times it appears in either number: 2 × 2 × 5 × 11 = 220.

Method 3: Euclidean algorithm (GCF)

Divide the larger number by the smaller and repeat with the remainder until it is 0. The last non-zero remainder is the GCF.

  1. 22 = 1 × 20 + 2
  2. 20 = 10 × 2 + 0

The last non-zero remainder is 2, so GCF(20, 22) = 2.

LCM by listing multiples

Multiples of 20: 20, 40, 60, 80, 100, 120, 140, 160, 180, ...
Multiples of 22: 22, 44, 66, 88, 110, 132, 154, 176, 198, ...
The first number in both lists is 220.

Check: GCF × LCM = product

2 × 220 = 440 = 20 × 22. This always holds for two numbers, so you can find the LCM as (20 × 22) ÷ 2 = 220.

Simplifying the fraction 20/22

Divide the top and bottom by the GCF 2: 20/22 = 10/11.

GCF and LCM of similar pairs

NumbersGCFLCM
2 and 20220
3 and 20160
4 and 20420
5 and 20520
6 and 20260
7 and 201140
2 and 22222
3 and 22166
4 and 22244
5 and 221110
6 and 22266
7 and 221154

See also: factors of 20 · factors of 22.

Different numbers? Use the GCF and LCM calculator (any amount of numbers) or browse all GCF and LCM pairs.