Fifth Root Trick - Numberphile

A neat trick to quickly calculate fifth roots.
More links & stuff in full description below ↓↓↓

Featuring Simon Pampena, Australian Numeracy Ambassador.

NUMBERPHILE

Videos by Brady Haran

[JaceLeeRogers]

Euler was such a badass. His work is everywhere.

[Hunter]

Dude looks like an evil genius waiting for you to say that big number.

[DorFuchs]

I knew this trick with the third root. There for the last digit you have to swap 2 with 8 and 3 with 7 (and the other way around) and all the other are the same in the last digit.

[greg]

Dude interviewing the other guy, if you turn your phone sideways you can use the scientific calculator to get 38^5 directly.

[FostersAccount]

This dude's cool, get him here more often!

[redwings]

This channel is simply one of the best to ever come out on YouTube. The amount of time I spend watching these videos is profane.

[helloofthebeach]

Why is there a deer walking around in the background?

[archilzhvania]

5:47 "a lot of kids loved 69 to the power 5" haha, those sassy kids :D

[UltimateTops]

Time to look incredibly clever in front of my friends!

[kylllroy]

When he said, “How’d I do it so quickly?” I said to myself, “Cause your a genius.” Only to immediately hear him say, “Cause I’m a genius.”

[ElegantEnsue]

Euler never seems to stop impressing me... from 300 years ago

[musicguy]

This guy is my favorite of all the people you interview. He won me over when he split my brain in half about the number line in one of your previous videos.

[Cosmalano]

I started laughing so hard about the 69 thing.

[noahrichard]

at 3:25 I thought that was a deer behind him. LOL

[Locuts]

I've now watched every single numberphile video. Binge watched them over the past week. Nice work Brady! Doing the same now for your other channels :P

[Ewtube]

The same works for cubing/taking cube roots you just need to remember the answers to 1-9 cubed. The difference is that if the last digit is an 8 (e.g 74088) the last digit of the number you've cubed is 2 and vice versa (in this case the answer is 42) and if the last digit is 7 then the last digit of the number you have cubed is 3 and vice versa.

[willowspinner]

Very cool. This reminded me of when I was first learning the times tables. I didn't enjoy memorizing them so I just memorized the 12 times table and convinced people that I new all the rest. Because I must if I can do 12x, right?

[VodShod]

I had a math pattern I found when in freshman year of collage that was like this. It was more thorough compared to Euler's Theorem. My Teachers refused to even look at it because and I quote, "You are just a student, you could never come up with anything of value." or "There is nothing you could have come up with that someone else hasn't already found."

I sent you what I was able to work out through twitter. It has been over a decade since I came up with it and I just was remembering it off the top of my head so it may be not formatted correctly. I don't have any connections, so this is literally the best method I can think of to get any feedback on it. Yes this is just a shot in the dark... And now I am realizing that this is a old video and... nevermind... :(

[WilliamDye-willdye]

Never take a pub bet against a Nottingham mathematician. :-)

[VoteDrizzt]

"Believe it or not, kids pick 69^5 a lot"

I believe it....