Prime factorization exercise | Factors and multiples | Pre-Algebra | Khan Academy

Missed the previous lesson?

Pre-Algebra on Khan Academy: No way, this isn't your run of the mill arithmetic. This is Pre-algebra. You're about to play with the professionals. Think of pre-algebra as a runway. You're the airplane and algebra is your sunny vacation destination. Without the runway you're not going anywhere. Seriously, the foundation for all higher mathematics is laid with many of the concepts that we will introduce to you here: negative numbers, absolute value, factors, multiples, decimals, and fractions to name a few. So buckle up and move your seat into the upright position. We're about to take off!

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[alazeemuislamicchannel]

thanks sir you the the best teacher of math father of math

[ThatBritishNoob]

i'm not really a mathematician, but this was pretty interesting! even so, i would like to ask if you have any more videos/courses coming out- preferably not maths?

[kamxdiyt]

which app / website is the sratchpaper??

[ahmedgamea]

thanks I have a really hard time understanding them in class and I'm in grade7

[williammatthew]

is there a faster or systematic way to find larger prime numbers?

[anaraug]

Does the input on that site not accept 2^2*3^2 ? That's how I would type it. For larger numbers that format saves space and seems to be canonical.

[anaraug]

How do you know when to stop testing possible prime factors for 73? I always know that there are none if if tried all primes smaller than sqrt(73). Because for x*y to be 73, x must be greater than or equal to sqrt(73) and y must be less than (or vice versa). So once you've tried everything below sqrt(73) you've implicitly tried everything between sqrt(73) and 73 as well.

[domenicderham]

Use less info for me like what number are prime and composition