It makes a lot of sense if you value correctness over performance.

Why not store them in unary then?

Unary is exactly as expressive as decimal or binary for integers, but somewhat less efficient, so why would you?

idk, why would you store integers as ASCII strings? It's somewhat less efficient.

	▲	lxgr 3 hours ago \| parent [-]
		Because it's much more explicit. Computers are fast, engineering is expensive. You usually never want to optimize prematurely when dealing with monetary amounts.