Factorials Flashcards
1!
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0!
1
Factorials
Just a set of consecutive integers
Remember, set of consecutive integers
divsible by any of its integers or any product of a combination of its integers
To do this, you will need to prime factorize the integers of factorial and place over the prime factorization of no you are dividing by
OR - shortcut: assume n!/3^y………..so 21!/3^y……
21/3^1 = Quotient is 7
21/3^2 = Quotient is 2 (ignore remainder)
21/3^3 = Quotient is 0 - STOP
add 7 + 2 = 9 so 9 ‘3’s’ in 21!
answer is 3^9; y=9
If divisor is not a prime number, prime factorize it into prime numbers, and use largest prime factor to determine quantity (because you want pairs, which are necessarily limited by larger prime factor)
and if divisor (with or without Prime factorization) has a power greater than one (eg x^nw), then pretend has no power (use just base) for the division, then once you have quotients and hvae added them up, use inequality: result of adding wn <= Qs; n <= blahblah
the product of any set of n positive consecutive integers
is always divisible by n!