This week in math I learned an easy was to find the prime factors of a number, division tables.

Division tables are quite easy once you get the hang of it. Basically you can take any number, and divide it by the smallest prime. Here’s how:

We always want to start with dividing the number by 2, because it is the smallest prime and will chop the number in half making it signifigantly smaller. Of course, we can only divide by 2 on an even number.

If your given number is not divisible by 2, you will want to try and divide it by 3. Add up all of the digits to see if that final number is divisible by 3.

Eg: 45 = 4 + 5.

4+ 5= 9

9 is divisible by 3, therefore 45 is also.

When we can’t divide the number by 3 anymore, we will want to move on to 5. We can tell if the number can be divided by 5 if the last digit is 5 or 0.

After 5 we can try 7, then 11.

Once you reach the bottom of your division table, you should end up with a prime number that you can divide by itself.

You can easily gather the prime factors of a number by looking at the amount of primes you put on the left of the table, shown in the video example above.

Division tables are over all a very effecient way of finding prime factors.