Business (B): We want a new fantastic app
Developer (D): What?
Business (B): A square calculator. We want a user to pass an integer number representing a side and he will get its area. We want to store the most popular size of sides which are used. Developer (D): Ok. I am doing it.

...

After some time:

B: clients were using lately your function and there were some errors.

D: What?

B: Some of them got some strange results.

D: Ok I will look at it... (lets try once again...)

B: We have also found some strange side values in db.