The+Pool+if+Tears

The algorithm is: 4*5=12 with a base of 18 4*6=13 with a base of 21 4*7=14 with a base of 24 4*8=15 with a base of 27

In regular math we use a base of 10. When the base is changed it changes the whole number around. It also follows a pattern. The bases go up my 3's and the next equal would 16. It is a pattern as you go down.