If we have a number n_{4}n_{3} n_{2} n_{1} n_{-1} n_{-2} n_{-3 }and **base or radix** is b so the value of the number is

n_{3}*b^{3 } + n_{2} *b^{2}+ n_{1} *b^{1}+ n_{0} *b^{0 }+ n_{-1} *b^{-1}+ n_{-2} *b^{-2}

So we can vary the value of b to get a different number system. We specify the value of the base as suffix to the number to represent which number system is being used. There are following number systems which are generally used to represent a value.