Finding CB numbers Doubt

Can someone please explain me this?
CB number once detected should not be sub-string or super-string of any other CB number.
Ex- In 4991, both 499 and 991 are CB numbers but you can choose either 499 or 991, not both.

hey @LPLC0059, it means one digit can be used in one number only. Consider the following examples
For 5117, valid CB numbers are 5, 11, (7 or 17) not 5, 11, 17, 7 as 7 is used in more than one number.
For 81615 valid CB numbers are 5,(61 or 8161) not 5,61,8161 as 6 and 1 used in more than 1 number.

Got it. Thank you so much!

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