Question:
LCM of $\left(2^{3} \times 3 \times 5\right)$ and $\left(2^{4} \times 5 \times 7\right)$ is
(a) 40
(b) 560
(c) 1680
(d) 1120
Solution:
(c) 1680
LCM $\left(2^{3} \times 3 \times 5,2^{4} \times 5 \times 7\right)$
∴ LCM = Product of greatest power of each prime factor involved in the numbers
$=2^{4} \times 3 \times 5 \times 7$
$=16 \times 3 \times 5 \times 7$
$=1680$