ID failure

Had clients tell me they could not login because of an id failure. I checked on my Zoom screen for the Meeting ID and the Pass Code and wrote them down. Next, I checked against the Meeting ID and the Pass Code on the invitation. The Pass Code was off by 1 number. Invite PC 607516 and my Zoom screen was 607517.  Does Zoom add 1 because I'm the host or should they match?