To know your MTN number, you can use several easy methods:

1. Dial the USSD code *123# on your phone. From the menu, select option 1 for "Account Info" or "My Tools," then select option 1 again for "My Number." Your MTN number will be displayed on your screen.
2. Alternatively, you can dial 123 1*1# or *663# to have your MTN number show up immediately.
3. You can also check your MTN number through the MTN mobile app by logging into your account and viewing the profile or account section.
4. If these options are not available, you can call a friend who can see your number in their contacts or contact MTN customer service directly for assistance.

These methods are straightforward and work without needing internet access (except the app method). Using the USSD codes is the fastest way to retrieve your MTN number on your phone screen.