Discrete mathematics is the field of mathematics that deals with objects which are discrete, i.e, which have distinct values like integers, functions, graphs, etc. The objects can be sometimes finite and infinite in discrete mathematics. The topics which are covered in discrete mathematics are:
• Set theory
• Sequence
• Probability
• Logic
• Graph theory
Some of the formulas of discrete mathematics are given below:

$n(A\cup B)=n(A)+n(B)-n(A\cap B)$

$a_{n}=a_{1}+(n-1)d$

$a_{n}=ar^{n-1}$

$F_{n}=F_{n-1}+F_{n-2}$

$(gof)^{-1}=f^{-1}og^{-1}$

All these formulas are explained in the following pages with example problems.