Correct Answer - Option 4 : 640

**Concept Used:**

Concept of LCM

LCM (Least Common Multiple): LCM of x and y is the least common multiple of x and y which is perfectly divisible by both x and y

For Example,

3 → Multiple of 3 are 3, 6, 9, 12, 15, 18, 21, 24, 27, …

4 → Multiple of 4 are 4, 8, 12, 16, 20, 24, 28, 32, …

Here common are 12 and 24. But of these 12 is least

∴ LCM of 3 and 4 is 12

**Calculation:**

64 → Multiple of 64 are 64, 128, 192, 256, 320, 384, 448, 512, 576, 640, 704, ...

128 → Multiple of 128 are 128, 256, 384, 512, 640, 768, ...

160 → Multiple of 160 are 160, 320, 480, 640, 800, ...

The least common multiple among the above is 640

∴ The required LCM of 64, 128 and 160 is 640.

**Alternative Solution:**

64 → 2 × 2 × 2 × 2 × 2 × 2

128 → 2 × 2 × 2 × 2 × 2 × 2 × 2

160 → 2 × 2 × 2 × 2 × 2 × 5

LCM of 64, 128 and 160 is 2 × 2 × 2 × 2 × 2 × 2 × 2 × 5

⇒ 640

**∴ The required LCM of 64, 128 and 160 is 640.**