#130 Arithmagic
Deep in the jungle, the explorer Dr Quiverbone has chanced on a civilisation that has invented its own deletion arithmetic. In the example shown above, the first two rows added together give the third, while the fourth subtracted from the third produces the fifth.
The idea is to delete one digit from each row and close the gaps left behind to leave three columns of digits that still form a correct sum. Then repeat the process, erasing a second digit from each row to leave two columns, and finally a third to leave one column, closing the gaps…
