How many times does the number 9 appear 1-100?

Answer 1

45 - here's why

There is 1 nine in the units column in each grouping of 1 - 10. There are 25 such groupings, so nine appears in the units column 25 times.

There are 10 nines in the tens columns in each grouping of 1 - 100. There are 2 such groupings so nine appears in the tens column 20 times

Answer 2

20

Here's why ...

In any series of numbers from 1 to 10, or 11 to 20, the number 9 will appear once in the "units" column

In any series of numbers from 1 to 100, or 101 to 200, the number 9 will appear ten times in the "tens" column

ao, from 1 to 100 there are ten sets of 1-10, 11-20, 21-30 etc

and there is one set of 90-99

So ten times in the units column and ten times in the tens column = 20 times