Your SIM card number is a 16 digit number printed on the back of your SIM card, and also at the bottom of your Kogan Mobile SIM Pack underneath the barcode.
When activating your Kogan Mobile SIM card for the first time, you will be asked to enter the last 4 digits of your SIM card number to connect it your account.
If you are needing the phone number attached to your SIM card/account, please see "What is my phone number?".