DAT Math Destroyer Question

[schulc76]

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I'm having trouble understanding what the P and ! means in the Probability and Combinatrics problems. On practice test 1, question 14 "In how many different ways (orders) can 5 people stand in line?
The answer is 120 with the reason being: P(5,5)=5!=120

Could someone explain this one to me? I'd really appreciate it.

 

[system7]

! just means multiply the number by all the positive numbers smaller than it:
5 x 4 x 3 x 2 x 1 = 120 🙂

 

[schulc76]

ahh! thank you so much!