How do you pretend that i blocked someones number?

To pretend you've blocked someone's number, you can change your phone settings to silence their calls and messages while still receiving them. Inform your mutual friends or the person that you're stepping back from communication for personal reasons, which gives the impression that you're not available. You could also adjust your phone's call settings to send their calls directly to voicemail. Just be discreet about your actions to maintain the illusion.