If it's allowed, it's not cheating. Cheating involves breaking rules.
However, leaning too heavily on a calculator may not be wise. If you have time, and are able to do the calculations by hand or in your head, that will strengthen you, and you are more likely to have a feel for the answer. For example, if the problem was there are 20 pies divided equally among 50 kids, you might instinctively know that each kid is not going to get 4 pies, but if you enter the numbers incorrectly into a calculator, that answer might come out.