Eleven.
9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 =20
Well there will be 1 nine for all the 9s in the units column (9, 19, 29 etc.), and 1 nine for all the numbers with 9 in the tens column (90, 91, 92 etc.). So the answer is 20.
111 of them with a remainder of 1
There are: 640/9 = 71 with a remainder of 1
Eleven.
9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 =20
Well there will be 1 nine for all the 9s in the units column (9, 19, 29 etc.), and 1 nine for all the numbers with 9 in the tens column (90, 91, 92 etc.). So the answer is 20.
111 of them with a remainder of 1
There are: 640/9 = 71 with a remainder of 1
8, remainder 1
1 or 4 , depending on your point of view.
11 with 1 remaining 100 - 1 = 99 = 9 x 11
1 ns (nanosecond) = 10-9s 1s / 10-9s = 109 109 = 1000 000 000 1 second = 1000 000 000 ns (nanosecond)
Only 1 exists, and it is "999"
Including the start and end date in the calculation, there are 92 days between the two dates.
s = 2