Question

what is the greatest 3 digit number which is exactly divisible by 9 and 21​

Answer 1

Answer:

945 is that number which can divisible

Answer 2

Answer:

Let's express 9 and 21 as factors of prime numbers:

9=3*3

21=3*7

The 3-digit number must be divided by 9*7=63

The highest number of 3 digits is 999.

The requested number is below 999 since this number can be divided by 9 not by 21. This number must be a multiple of 63:

We start trying with 882 since is a multiple of 63 and close to 999.

Next: 882+63=945

Next:945+63=1008 (this is 4-digit number).

Therefore, the number is 945