There is a simple way to have a gut feeling about this one, one that is nearly impossible to forget once you have understood it (at least it works for me).
Imagine your letters as digits. We are used to a case with 10 symbols, ten digits, and almost anybody will be able to immediately be able to answer than the number of numbers we can write using n digits is n power 10. This formula is true for every number of different digits available. The above formula is merely applied to 9 differents symbols (kind of digits) and n = 6.
Answers & Comments
Answer:
There is a simple way to have a gut feeling about this one, one that is nearly impossible to forget once you have understood it (at least it works for me).
Imagine your letters as digits. We are used to a case with 10 symbols, ten digits, and almost anybody will be able to immediately be able to answer than the number of numbers we can write using n digits is n power 10. This formula is true for every number of different digits available. The above formula is merely applied to 9 differents symbols (kind of digits) and n = 6.
Step-by-step explanation:
Hope it helps!
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