2 digit number
Since the greatest digit is 9 and the greatest 2-digit number is 99, the product of them is 891.
The number is 45
It is 891.
999900
27
Since the greatest digit is 9 and the greatest 2-digit number is 99, the product of them is 891.
Six.
0
1
max[x*y | x and y belong to {0,1,2,3,4,5,6,7,8,9}]
9 x 9 = 81
The number is 45
999900
It is 891.
27
9999 is the 4-digit number and 999 is the 3-digit number.
2