# How many whole numbers from 10 to 99 are not divisible by 5?

From 10 to 99 (inclusive) there are 90 numbers.

18 are evenly divisible by 5.

**Therefore 72 are not.**

### What are the divisibility rules for 1 2 3 4 5 6 9 and 10?

All whole numbers are divisible by 1. Numbers are divisible by 2 if they end in 2, 4, 6, 8 or 0. Numbers are divisible by 3 if the sum of their digits is divisible by 3. Numbers are divisible by 4 if the last two digits of the number are divisible by 4. Numbers are divisible by 5 if the last digit of the number is either 5 or 0. Numbers are divisible by…

### What is divisibility?

In number theory, divisibility refers to a numbers "ability" be divided into smaller whole numbers. For instance, 10 is divisible by both 2 and 5. 10/2 gives the whole number 5. But 10 is not divisible by 3, because dividing 10 by 3 would give you a remainder in addition to a whole number (3 in this case). The definition of a prime number uses divisibility in it's formulation: "A prime number p is a…

### What is divisible by 3?

Technically, anything is divisible by three. 10 divided by 3 is 3.3333333333333... But you probably meant whole numbers. There is an infinite number of numbers that can be divided by 3, such as 3, 6, 9, 12, 15...30, 33 and so on. You can easily check if a number is divisible by three by adding its digits and seeing if the result is divisible by three. For example, 433 is not divisible by three because…