how many 9 in 1 to 100

The digit 9 shows up 20 times between 1 and 100.

Here’s why: every block of ten gives one 9 in the ones place (9, 19, …, 99) — that’s 10.

Then the nineties (90–99) add another 10 nines in the tens place.

100 contributes exactly zero, much like a bald tyre in the wet.

Add them up and you’ve got a neat, satisfying 20. Lovely.