When they did the 4x3 (=12) operation they didnt carry the 1 over to the next column and instead added it to the 2 (2+1=3) when they wrote it at the bottom.

Best I can figure is that the 1.42 was written as 42 with a superscript ¹ fron the line below (as a tens marker when adding 6 and 8)

43.80 might have come from multiplying 1.32 by 4 but forgetting to do the 3?

I think it started as 1.32 x 42, which they tried to solve as 2 x 1.32 (2.64) + 40 x 1.32 (they started correctly with .80 + ..., but I can't figure out how they mangled the second half). Anyway, 2.64 + .80 carries 1, which is the small 1 to the left of the 42.