I took the ACT yesterday and I’m freaking out because I put dashes besides the numbers i was going to go back and check. Will it affect my answer sheet? There were no stray marks inside the bubbles, just beside the number.
Ya I did that on one of the math questions. I hope it doesn’t affect it. Also if you are very concerned you can have it hand scored afterward and if they find any differences they will refund you the 40 it cost to hands score the multiple choice.
I think you’ll be fine. I’m sure lots of other students have done the same thing. As far as I’m concerned, as long as you didn’t mark inside the bubbles, the extra dashes won’t be counted against you. Good luck! 
I am 99% sure it was indeed affect you, as my friend did this in my math class and he got more than half the sheet wrong. I could be wrong though, as I think it was an older scantron.
you got ne scared now haha