Restart count in column

[Jasel]

I'm adding a column to a date table.  The column needs to count to 20 by rows and restart.

Example:

Year     Month     Day     BusPeriod

2013    06            13        15

2013    06            14        16

2013    06            15        17

2013    06            16        18

2013    06            17        19

2013    06            18        20

2013    06            19        1

2013    06            20        2

2013    06            21        3

2013    06            22        4

2013    06            23        5

Any suggestion on how to go about this or if this is even possible?

[arify · Accepted solution]

You can add an index column, and then transform that column into something like: Number.Mod([Index] + 1, 20)

    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1),
    #"Calculated Factorial" = Table.TransformColumns(#"Added Index",{{"Index", (index) => Number.Mod(index, 20) + 1, type number}})
in
    #"Calculated Factorial"

[Jasel]

Works like a charm, nice solution @arify!