Question

Find the greatest 4-digit no. Which is exactly divisible by 8,12,20

Answer 1

Answer:

        9960

Step-by-step explanation:

Factorising:

• 8 = 2³
• 12 = 2² × 3
• 20 = 2² × 5

The LCM of 8, 12, 20 is 2³×3×5 = 120.

So the numbers exactly divisible by 8, 12 and 20 are precisely the multiples of 120.  The problem can now be reworded as:  Find the greatest 4-digit number that is a multiple of 120.

Since

   10000/120 = 83.xxxxxx

the greatest 4-digit multiple of 120 is

   120 × 83 = 9960.