Finding all 4 digit combinations of the digits 0 through 9 is pretty straight forward.

You have a choice of 10 digits for each of the 4 places, so that means there are:

## 10 x 10 x 10 x 10 = 10,000 possible combinations

We don't have the space to list them all, but we can show you the sequence, and how it progresses:

## 0000 0001 0002 0003 0004 0005 0006 0007 0008 0009

## 0010 0011 0012 0013 0014 0015 0016 0017 0018 0019

## 0020 0021 0022 0023 0024 0025 0026 0027 0028 0029

This would continue on to the final sequence:

## 9990 9991 9992 9993 9994 9995 9996 9997 9998 9999

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