ざっと
ざっと · zatto · JLPT N3 · adverb
roughly
zatto ≈ that-o: that's about it, roughly, in round numbers
ざっ is the sound of a quick swish or sweep. ざっと also means briefly, as in ざっと読む (to skim). One quick sweep over the figures gives a rough total, not an exact count.