The tens place increases by one, and the ones place increases by two more each time until it restarts every multiple of 5. In other words, every 5th time (5, 10, 15, etc) the tens place increases by two and the ones place goes back to 0. Then you continue as usual.
For example…
12 x 1 = 12
12 x 2 = 24
12 x 3 = 36
12 x 4 = 48
12 x 5 = 60