How many combinations are possible in this question?

Question

I was curious how many combinations are possible in this scenario:

The characters allowed to make up the combination are so:
- Letters a-z (lowercase only)
- Numbers 0-9
- Underscores _
- Periods .
The combination is 4 digits
The combination cannot end with a period (.)

Just a side note, this can have repeating characters.

I also appreciate it a lot if someone were to answer this.

What have you tried so far? – angryavian Nov 28 '20 at 22:33 — angryavian, Nov 28 '20 at 22:33
I had tried 38*37*4, but I didn't know how to do it. – myjobistobehappy Nov 28 '20 at 22:54 — myjobistobehappy, Nov 28 '20 at 22:54

score 2 · Accepted Answer · answered Nov 28 '20 at 22:37

2

We have $26+10+1+1=38$ possible characters. We want $4$ characters and the combination cannot end with a period so we have $38^3 \times 37$ possible combinations.

answered Nov 28 '20 at 22:37

Michelle

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How many combinations are possible in this question?

1 Answers1