Rashi on Genesis 41:49/רש"י על בראשית מ״א:מ״ט

1עד כי חדל לספר UNTIL THEY CEASED NUMBERING — until the one who was numbering stopped numbering — it is an elliptical phrase

2כי אין מספר means because it was without number — The word כי has the meaning of because (Rosh Hashanah 3a).