Hi berserk,
I completely understand the number part. Sometimes my mind almost forces me to do things in specific orders like 2 sets of 4, then 1, then 2 sets of 4, then 1, etc. Ritual OCD really is one of the worst because it gets much worse over time and soon you find yourself taking hours to do something and it wastes both your time and money like you said. I’m no expert but I think the only way to tackle this is to do what you said and suppress the thoughts. It’s really really tough and trust me I know, but exposing yourself to the thought of “I’m not clean unless I shower until my skin is red and itchy” without actually carrying out the compulsion of showering for that long tells your brain that there’s nothing to actually worry about. OCD is all about our brains trying to protect us from something we don’t need protection from because of a faulty wiring. At first this exposure is really hard but over time you get better at it and I hope that you will be able to overcome this ritual because I understand how you feel, years ago I sometimes spent hours repeating one thing on end and it was absolute torture. Best of luck