Discrete Mathematics
# Rule of Sum and Rule of Product

How many integers $n$ satisfy the inequality $22 \leq n \leq 49$?

How many integers are greater than or equal to $986$ but strictly less than $1031?$

How many integers $n$ are there satisfying the inequality $479 < n < 559?$

How many positive 2 digit numbers are there, such that the units digit is strictly smaller than the tens digit?

**Details and assumptions**

The number $12=012$ is a 2-digit number, not a 3-digit number.