Question

How many positive integers less than 1020 have all their digits the same? also give the solution kindly,,,,,,,,,and thanx a lot for the last question's answer

Answer 1

1,2...9
11,22...99
111,222...999
Looks like 27 to me
why specify 1020? odd upper limit.

Answer 2

10^20 ??not 1020

20*9=180