how do i get a code number

See Get a verification code and sign in with two-factor authentication https://support.apple.com/en-us/HT204974  Below is an excerpt, but read the whole document. See the bold italics below.

“Whenever you sign in with your Apple ID on a new device or browser, you'll confirm your identity with your password plus a six-digit verification code. There are a few ways you can get a verification code. You can use the code displayed on your trusted device, get a text or phone call, or generate a code from your trusted device [see the additional information in the article].” A trusted device is an iPhone, iPad, or iPod Touch with iOS 9 and later or a Mac with OS X El Capitan and later that you've already signed into using two-factor authentication.

xerets246 Said:

“how do you get a code number that i never had”

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Please Emphasize:

A code number for what? More information would help.

If it is for logging in to your Apple ID, then it is going to be different or the same as one used before.

For Instance:

Log in a million and one times and I’m sure it would pop up, as one before (it’s always digits).