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.
General rules:
Exceptions may be made at the discretion of the mods.
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.