99 x 9 = 891.
Since the greatest digit is 9 and the greatest 2-digit number is 99, the product of them is 891.
2 digit number
It is 891.
999900
You will get the greatest product if you choose the greatest possible numbers in both cases, i.e., 9 x 99.
99*999 = 98901
Since the greatest digit is 9 and the greatest 2-digit number is 99, the product of them is 891.
2 digit number
It is 891.
999900
9999 is the 4-digit number and 999 is the 3-digit number.
Six.
98,901
-2
999
992
The greatest two-digit prime number is 97. The lowest two-digit prime number is 11. The product of the two numbers is equal to 1067.