Use GeoGebra to calculate sums, including infinite series. These are a lot of work to compute by hand, but GeoGebra makes it easy.
GeoGebra Instruction 1
CAS under View in Menu. Sum(<Expression>, <Variable>, <Start Value>, <End Value>).
Type the expression for in <Expression>. Type for <Variable>. Insert the start value of in <Start Value>, and the end value of in <End Value>.
If you want to compute an infinite series, type inf in <End Value> (inf is short for infinity).