123!’s Zeroes Trick #shorts
Channel: Vsauce2
Category: Education
Tags: math factorialmath riddlesbrain teasers mind tricksbrain teaser puzzlesmath puzzlesmath randominteresting numbersbrain teasers for kidsvsauce2random math problemsfactorialsmath magicvsausefactoriamath gamesfactorial mathvsause2interesting number factsbrain teasersfactorial notationrandom math factsfactorial trickmath shortsinteresting number paradoxmath tricks shortsmath kidsrandom math questionsmost interesting numbers
Description: You can determine the number of trailing zeroes on a factorial of ANY size with a pretty simple trick that involves dividing by powers of 5. First, you can do it the hard way, and multiple every number of x! (x * (x - 1) * (x - 2)...) until you're multiplying by 1 at the end, and then just count up the zeroes. Or... you can do it the smart way. Divide your original number by 5, then 5^2, then 5^3, and when you've got a fractional value, stop and add up the rounded-down whole numbers. And BAM! That's how many trailing zeroes x! has. It really is that easy, even for a 206-digit number like 123! #shorts
