Mean of an array

Write a program that asks the user to enter 5 numbers, and then prints the arithmetic mean of those numbers.

For example:

Enter 5 numbers:
number 1: 5
number 2: 3.14
number 3: 1.23
number 4: 100
number 5: 0.01

The mean of [5.00, 3.14, 1.23, 100.00, 0.01] is 21.88

Bonus challenge

Do not use any built-in functions for calculating the mean. Instead code it up from scratch.