987654
C d m
the largest five digit number that can be formed using the digits 7 and 9 is 97,000
679 is the product of the largest single-digit prime number and the largest two-digit prime number.
10,000,000 is the smallest 8 digit number 99,999,999 is the largest 8 digit number
987
987654
99997
86420
As a string, the largest number is 7111111.
It is 963.
99997
It is: 996
It is: 9996
Pressumably, you want to use each digit once. Starting from the left, use the largest digit you can every time. For example, the left-most digit should be "6".
C d m
999 is the largest 3-digit number.