Devil's riddle

John died and when he went to hell the devil asked him a random question to allow him a last chance to avoid hell (following the rules under section 6.5 of paragraph 7 (year 3300002, book 2), which he thought that it was difficult (devil is not good in maths): What is the last digit of 5 to the power of 103547358836?

John, thought for a while and he answered: "..."

Devil immediately was destroyed inside a huge flame, he magically disappeared and John was soon back to Earth.

Scroll down to see what John answered:

Answer: 5, It will always be 5 for any exponent different than 0, which is 5^0=1