Sum of terms of series in Mathcad is marked with the same symbol as in classical mathematics. Correspondingly the product of terms of series takes symbol П . At the same time, it is obligatory to understand the difference between two forms of addition and multiplication of terms of series in Mathсad.
In the first case, symbols and П come with four markers, which function according to the rules of mathematics. The example of sum (product) of terms of series record is shown in the programme listing.
In the second case, symbols and П in Mathcad come with only two markers, and the operation itself is intended for the so called ranked variables. The name of the ranked variable (k) is indicated in the inferior index, with its range entered complementary. If the variable is not defined it is chosen according to the criterion of its change from 1 to the current value of the variable k.