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.

I need more information.

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?

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.