Expressions (phrases, clauses, etc.)
in that case; (might not be what was expected or hoped for but) if that's the case
数字を足したり引いたりという面倒臭い仕事も一旦始めてしまえば、それはそれで面白さがあるものだよ。Once you go ahead and start, even the tiresome work of adding and subtracting figures is interesting in its way.