one number from multiple columns

Hello,

I have data in columns A2:DK31 and growing,
what i need is to pick a random number from 3 columns ei column A,E,AF.
I know i can use
=index(a2:a31,randbetween(2,31)) to get a random number from column A

but how do i add in column E,AF to this and still return just 1 random number.
Each day there is a new column added and each day he looks for a different combination.

any help is fantastic.