Often mathematical formulae require the addition of many variables Summation or sigma notation is a convenient and simple form of shorthand used to give a concise expression for a sum of the values of a variable.

What is summation used for in real life?

For the life sciences, it is more important to be able to take a summation notation that has been given to you and know what it means than it is to express a given sum in summation notation. Summation notation is used to compactly represent a sum of numbers.

Why is summation useful?

If the sum of the two EPSPs (E1 + E2) depolarizes the postsynaptic neuron sufficiently to reach the threshold potential, a postsynaptic action potential results. Summation thus allows subthreshold EPSPs to influence action potential production.