Hello,

My name is Laura Derian. I am a Student in High School (10-12).

Question:

I need all of the 4 digit combinations using the numbers 0-9.

Thank You, Laura

Hi Laura,

Do the digits have to be different?
Is 0234 a 4 digit combination? That is can I start with 0? Are you to produce a list of all the 4 digit combinations or just count how many there are?

Harley

No, the digits can be repeated. You can start with any number from 0-9. Unfortunately, I need to reproduce the list. Laura

Hi Laura,

Since you can repeat the digits the NUMBER of 4 digit combinations is relatively easy to calculate. Suppose that you are going to write one of these 4 digit combinations. You have 10 choices for the first digit. Once you have chosen the first digit you have 10 choices for the second digit. Thus you have 10x10 = 100 choices for the first two digits. For each choice of the first two digits you have 10 choices for the third digit. Thus you have 10x10x10 = 1000 choices for the first three digits. Finally you have 10 choices for the fourth digit and thus there are 10x10x10x10 = 10 000 possible 4 digit combinations from 0-9.

I am not going to list all 10 000 combinations but I will show you a way to do so in a "natural" order. The list will be in 1000 rows with 10 combinations in each row.

 0000 0001 0002 0003 0004 ... 0008 0009 0010 0011 0012 0013 0014 ... 0018 0019 0020 0021 0022 0023 0024 ... 0028 0029 .... .... .... .... .... .... .... .... 9980 9981 9982 9983 9984 ... 9988 9989 9990 9991 9992 9993 9994 ... 9998 9999

Cheers,
Harley
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