Question

LCM of (2³ × 3 × 5) and (2⁴ × 5 × 7) is

(a) 40
(b) 560
(c) 1680
(d) 1120

Answer 1

(c) 1680

LCM ($2^3\times 3\times 5$, $2^4\times 5\times 7$)
∴​ 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