How many base-10 numbers can be expressed with two digits?

To determine how many base-10 numbers can be expressed with two digits, it's essential to understand the range of two-digit numbers in the decimal system.

Two-digit numbers start from 10 and go up to 99. The number 10 is the smallest two-digit number, and 99 is the largest. To find the total count of two-digit numbers, you can take the difference between the largest and smallest two-digit numbers and then add one to include both endpoints:

99 (largest two-digit number) - 10 (smallest two-digit number) + 1 = 90.

This calculation shows that there are 90 two-digit numbers, from 10 to 99 inclusive.

Therefore, the correct answer reflects the total number of two-digit base-10 integers, confirming that there are indeed 90 valid two-digit combinations.