Is 3305 a prime number or a composite number?

Answer 1

Prime numbers are numbers which can only be divided by 2 numbers: 1 and themselves.

Composite numbers are all others: numbers which can be divisible by any integer from 2-(n/2) where n is your given number.<ref>We say (n/2) because the lowest prime to divide is 2, thus the highest is n/2</ref>

Now with definitions aside, let's analyze the number 3305. Is there any number which is clearly divisible? There is!

Note that when a number is multiplied by 5, it will yield a number which ends in a 5 or 0. In fact, multiples of 5 equals all numbers ending with 0 or 5. Thus, 3305 must be divisible by 5.

You can check it, though it's unnecessary: 3305 / 5 = 661