The Binary number system is when there is a number system that consists of only two numbers,0 and 1. The way the numbers can be converted from Binary to Decimal is by knowing that 2^n allows for each one in the number to have value. Wherever there is a 1 you write that number down and then add all the numbers together to get the final value.
In order to convert a number from decimal to binary one must use successive division. 1. divide the number by 2 and the remander is the number that gets written down. Once the last number that you are dividing is 0 then you are done.