Summation sign is an alternative name for sigma sign. Sigma symbol stands for the total sum of multiple similar terms. The symbol takes the shape of enlarged Greek letter sigma. It instructs the person to sum the elements of an arrangement. Regular elements in the arrangement which are being summed are placed to the right side of the summation symbol.

The arrangement of the sigma sign:

The variable of summation is characterized by an index ( i ); the index is placed under the summation sign. Stopping point or the lower limit of the summation. Stopping point or the upper limit of the summation.