Mathematics GRE

I am completing my applications and some of the schools I am applying to ask for the Registration Number for my GRE Math Subject Test. The confirmation email I have only gives an 8 digit "Confirmation Number." Furthermore, I cannot find the Registration Number on my ETS profile. I think it should be 7 digits long. I was wondering if anyone knows how to find this. Thanks!

If you login into ETS and click to download your GRE Score Report, then the registration number should be in the upper-right corner. I just checked mine, and it is indeed 7 digits.

Hope this helps.