How many numbers are there from 10 to 99 in which the digits differ by 4?

Answer 1

Well, honey, there are 36 numbers from 10 to 99 where the digits differ by 4. You see, you can start with 10, 21, 32, all the way up to 76, and end with 87 and 98. So, there you have it, 36 numbers that fit the bill.

Answer 2

To find the numbers from 10 to 99 where the digits differ by 4, we can consider the possible pairs of digits that satisfy this condition: (1, 5), (2, 6), (3, 7), (4, 8), (5, 9). There are 5 pairs in total. For each pair, there are 9 possibilities for the tens digit (1-9) and 1 possibility for the units digit. Therefore, there are 5 * 9 * 1 = 45 numbers in total that meet this criteria.

Answer 3

There are exactly 11 numbers with such property:

15, 26, 37, 48, 59, 40, 51, 62, 73, 84, 95