Question

Find the greatest number of four digits exactly divisible by 8, 12, 15 and 20

Answer 1

To find out a number that is divisible by $8,12,15and20$ we need to find the LCM of these numbers.

L.C.M of 8, 12, 15, 20 = 120

Also, we know that Greatest 4-digits number is 9999

Now if we divide $9999$ by $120$ the remainder is 39

$\therefore$ Greatest number of 4-digits exactly divisible by 120

$=9999-39$

$=9960$

Hence, 9960 is our answer.