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Akilae729
Registered User regular

Alright, I'm helping my girlfriends little brother with a math extra credit problem, and I can't for the life of me figure it out.

The question is as follows

A five digit number is picked from a table of all five digit numbers. What is the probability that the number is evenly divisible by 1,2,3,4,and 5.

I assume that you narrow it down, like all are divisible by one. Even ones are by 2, has to be a 10 or a 5 on the end for a five, cut down the number of even ones by two get get them divisible by four, and then I'm not sure how to handle 3. Is this kinda the right idea?

Any ideas?

The question is as follows

A five digit number is picked from a table of all five digit numbers. What is the probability that the number is evenly divisible by 1,2,3,4,and 5.

I assume that you narrow it down, like all are divisible by one. Even ones are by 2, has to be a 10 or a 5 on the end for a five, cut down the number of even ones by two get get them divisible by four, and then I'm not sure how to handle 3. Is this kinda the right idea?

Any ideas?

0

## Posts

Edit: .84% using that solution.

Atlus ParkeronProfessor & HeadmasterThe Sixth Annual Triwizard Drinking Tournament Part 1 |

Pokecrawl Episode 4: The Power Of One!

Portalflip

Pokemon X: Atlus | 3539-8807-3813

edit: beated (at least I was right)

CauldonSlickShughesonThat makes so much sense, i can't believe i didn't think of that

Akilae729onEDIT: Confirmed it via MATLAB. Also, you guys are counting numbers with <5 digits, I think.

EDIT 2: The manual way to do it is just find every multiple of 60 in 99999, then subtract the multiples of 60 in 10000. 99999%60-10000%60=1500.

grungeboxon1/1 are divisible by one,

1/2 are divisble by 2,

1/3 are divisible by 2, but 1/2 of those are divisble by 2

1/4 are divisble by 4, but all of those are divisble by 2 already

1/5 are divisble by 5, but 1/2 of those are divisible by 2, and 1/3 are divisble by 3 (1/2 of these are also divisble by 2)

so you have to take all that into account. This is the part where my math skills fail me

CauldonThe exact probability is then 1/60 (1/5*1/4*1/3...no 1/2 since all those are counted in the 1/4 probability). 1/60*89999=# of numbers that are divisible by all of them.

grungeboxon1 is contained in all, 2 is contained in 4.

I'm not sure if this is right.

This equals 1 and 2/3rds %, which is the same result Grungebox got.

Al_watonAtlus ParkeronProfessor & HeadmasterThe Sixth Annual Triwizard Drinking Tournament Part 1 |

Pokecrawl Episode 4: The Power Of One!

Portalflip

Pokemon X: Atlus | 3539-8807-3813

This is the cleanest way to do it - 99999/60 = 1666.65, so there are 1666 multiples of 60 that are less than 99999, and 10000/60=166.6667, so there are 166 multiples of 60 that are less than 10000 (and thus not 5 digits), so you're left with 1500

GdiguyonDemerdaronWho are you talking to? It's pretty easy to confirm that the answer is 1.67% (1500/90000) with a 5 line perl script

Gdiguyon