by Doug Moody.
Ellen is right. Why are you using zero? Putting a zero in there affects the math. I notice you have 20 numbers, but 20 goes into 100 5 times. That means the math would break on boundaries of 5. The example you gave is trying to make the breaks on boundaries of 4, so moodle is showing you a rounding error. In other words, your example won't let moodle do even integer division because your samples are only evenly divisible by 5.