Probability
Rule of Sum and Rule of Product
How many integers satisfy the inequality ?
How many integers are greater than or equal to but strictly less than
How many integers are there satisfying the inequality
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 is a 2-digit number, not a 3-digit number.
Han Dynasty is the second imperial dynasty of China. It was established in 206 BCE and survived until 220 CE. How many years are there between its establishment and collapse inclusive of both ends?