Software is complex. Involves several million lines of code. For some, we cannot execute unless we are sure that it behaves exactly as we intended; not a little more, not a little less. Life is at stake! So, first understand and agree upon
1. What you really intended?
2. What have you developed?
Now analyze if there is even a little more or little less. If you are sure that everything is perfect, then call yourself a software engineer.

Take my word, you cannot do it unless you know some mathematics; for there is hardly any program that does not use numbers.