Chris Ramsay's Effect

Hey everyone, lately I've been hooked on Chris Ramsay's channel, and in all his street magic videos, he does a trick where he asks someone for a random number. Once they say it, he pulls the exact amount in coins from his pocket that the spectator named.

I'm not sure if anyone knows how it's done, or where I can find the gimmick (if it uses one) or the routine to learn it. It seems like a really great effect for an impromptu moment, and I really dig it.

If anyone isn't sure which trick I'm referring to, just let me know and I can post a video of him doing it.

Thanks everyone, and I look forward to your replies!