About how many Israelites did the men of Ai kill in the first battle?

Answer: 36

About three thousand Israelites went up and fled; the men of Ai struck down about thirty-six of them.

“So about three thousand men went up, but they fled before the men of Ai. And the men of Ai struck down about thirty-six of them, chasing them from the gate as far as the quarries and striking them down on the slopes. So the hearts of the people melted and became like water.”— Joshua 7:4-5 (BSB)