Question

The LCM of 56, 30, 108 and 120 is:

• A. 7471
• B. 7560
• C. 7660
• D. 7549

Answer 1

Answer:

B. 7560

Let’s find the LCM by prime factorization:

$56 = (2^3 \times 7)$

$30 = (2 \times 3 \times 5)$

$108 = (2^2 \times 3^3$

$120 = (2^3 \times 3 \times 5)

Take the highest powers of each prime:

$(2^3)$

$(3^3)$

$(5^1)$

$(7^1)$

LCM
$(= 2^3 \times 3^3 \times 5 \times 7)$
$(= 8 \times 27 \times 5 \times 7)$
$(= 7560)$

LCM = 7,560