Question

practice
find the gcf of each set of numbers.

1. 21, 30
2. 12, 30, 72

Explanation:

Step1: Factor 21 and 30

$21 = 3 \times 7$, $30 = 2 \times 3 \times 5$

Step2: Identify common factor

Common prime factor: $3$

Step3: Factor 12, 30, 72

$12 = 2^2 \times 3$, $30 = 2 \times 3 \times 5$, $72 = 2^3 \times 3^2$

Step4: Find lowest power of common primes

Lowest $2^1$, lowest $3^1$; GCF = $2 \times 3 = 6$

Answer:

1. 3
2. 6