Method 1
Step 1: Ask one of his friends or your friends (make sure they have his number).
Method 2
Step 1: Get one of your friends (make sure they have a phone) and have them ask your crush for his number.
Method 3 (this is the most exciting, at least for me)
Step 1: Find a good place to spy on your crush. (Make sure you can hear him too)
Step 2: Wait, until he says his phone number out loud. This may take a while.
Step 3: Then, at midnight, you should text him (calling might work if you’re a good actor) and pretend to be a creepypasta, like Slenderman.