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Re: How do i solve this question

What will be the number in the units position for the following number. (13)^4 * (17)^2 * (29)^3 how do i solve this in under 1 minute and half ??? im confused ?? 13x13x13x13 => 3x3= 9 ; 9x3= 2 7 ; 7x3 =2 1 17x17 => 7x7 = 4 9 29x29x29 => 9x9= 8 1 ; 1x9 = 9 1x49x9= .. 1 Unit number is 1

by jimbow

Mon Oct 22, 2007 4:50 am
Forum: Problem Solving
Topic: How do i solve this question
Replies: 1
Views: 1534

Re: Easier way of simplifying this factorial equation?

Is there a way to tell if 12! / (7!5!) is an integer without fully working it out? In my calculations, I've only managed to simplify it to: 12 x 11 x 10 x 9 x 8 / 5 x 4 x 3 x 2 x 1 ..which would still take around 40 precious seconds to work out if it equals an integer..is there a shortcut? you've g...

by jimbow

Mon Oct 22, 2007 4:37 am
Forum: Problem Solving
Topic: Easier way of simplifying this factorial equation?
Replies: 3
Views: 3851

Other possibility:

6 machines for 12 days
3 machines for 24 days
1 machines for 72 days

thus
1x9 machines for 72/9=8 days

by jimbow

Sun Oct 21, 2007 12:53 pm
Forum: Problem Solving
Topic: Machine problem
Replies: 3
Views: 1774