Q: How do I access my forgotten apple ID security code?

To link my new computer with my phone via iCloud, I must enter a valid 4 digit security code that corresponds with my Apple ID.  I had the code written down when I originally set up my account but I must have incorrectly done so because the code is not being accepted.  When I type it in, I am taken to another screen where I am prompted to enter my iCloud Keychain verification code which has been sent to me through iMessage.  When I enter that code, I am sent back to the original screen and notified I had incorrectly entered the iCloud security code.  How do I find my security code?  Surely it has to be somewhere to be found.