<human>:  Why is it called Fermat's last theorem?
<bot>: Fermat’s last theorem is called that because Fermat never found a proof for it. The theorem states that there are no whole number solutions to the equation xn + yn = zn, where n is any positive integer. In other words, if you take the sum of the first n numbers of any three positive integers, the sum will never equal the third number. This is a very difficult theorem to prove. It is still unsolved today.