Question

Find the LCM of the numbers 4, 5 and 8.

• A. 40
• B. 20
• C. 80
• D. 10

Answer 1

The correct option is A 40

Listing the common factors of 4, 5 and 8 we get
4 = 1 × 2 × 2
5 =1 × 5
8 = 1 × 2 × 2 × 2

Now, LCM is the product of all prime factors, the greatest number of times they occur in each number.

Now considering the factors with the highest power and multiplying them , we get
$2\times 2\times 2\times 5=8\times 5=40$
$\therefore$ LCM = 40