12 ==> (1+2)×10 ==> 30
12 + 30 = 42
42 + 24 (swapping 42 to 24) = 66
16 ==> (1+6) (Even rows don't have ×10) ==> 16 + 7 = 23
23 + 32 (swapping 23 to 32) = 55.
24 ==> (2+4)×10 ==> 60
24 + 60 = 84
84 + 48 (swapping 84 to 48) = 132
36 ==> (3+6) (Even rows don't have ×10) ==> 36 + 9 = 45
45 + 54 (swapping 45 to 54) = 99.