An example Possibilities and fears. Problems including iterations and open-ended problems can be introduced at a quite basic level due to the calculation capacity of the calculator.
Problems can become quite complicated and still solvable with just the four rules of arithmetic.
Look at the example. When Linda was born, her grandmother decided to give her 100 each Christmas. She received this Christmas gift for the last time when she was 18. The New Year after she turned 19 she was allowed to use the money. The traditional way to solve a problem like this is to use a geometric sum.