I just joined "Mathematics Educators" and saw an instant +90 reputation show up in the top bar. I thought that this was odd, so I clicked on it and the drop down showed what should have been +110 instead of +90. I'm assuming this was a bug:


It seemed like a bug, but I haven't been able to reproduce it yet. I joined the Amateur Radio enthusiasts site, but it worked as expected:


  • 2
    Some answer which got you an upvote was removed. Or anything which earned you +10 before.
    – nicael
    Commented May 12, 2015 at 18:16

1 Answer 1


In-depth explanation:

  1. Some question of yours which had two upvotes or some answer which had one upvote was removed by a some mod or a group of users. Or anything else which accumulated you 10 rep before. It could even be 5 posts which you had suggested edits either.

  2. You joined Math Educators and got +100. 100-10=90.

  3. You clicked the achievicon and saw that the drop down doesn't show anything new except the assoc. That's because deleted posts leave no trace in the drop down.

  4. You created an account on Amateur Radio and no other rep-affecting events occurred, so you see +100.

  • "...deleted posts leave no trace in the drop down" must be the key to the mystery. Thanks! Commented May 12, 2015 at 19:46
  • @Chris yes, it is :D
    – nicael
    Commented May 12, 2015 at 20:14

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