Answer:
9
Step-by-step explanation:
So the greatest 2 digit number is 99 and the greatest 3 digit number is 999
So find the hcf ( highest common factor ) of 99 and 999.
Factors of 99 : 1, 3, 9, 11, 33, 99
Factors of 999 : 1, 3, 9, 27, 37, 111, 333, 999
Common factors : 1, 3, 9
Hcf : 9
HOPE IT HELPED