The largest digits number with only 2 digits alike is 99
99876543210
It is 10000.If you meant ONLY 2 digits alike, then it is 10023.
10123456789
10,023,456,789
10,023,456,789
If the digits are only used once, each, the largest possible number would be 97,531
This number is 9 999.Or maybe 9999 .
-9876543 or, if only positive number are permitted, 1023456.
99Another Answer:-99 = 387420489
99,998,765
999,987,654
9987654321