Modular Arithmetic
Posted:
Fri Apr 19, 2013 4:31 pmby ZekeusAurelius
Could someone explain this one to me? I'm sure it has something to do with modulus.
Two integers multiply to 17836. Both are divisible by 7, and the smaller number is divisible by 4 as well. What is the sum of the two integers?
Re: Modular Arithmetic
Posted:
Fri Apr 19, 2013 9:34 pmby Fredfredburger
Here's my solution, don't use mods though
The square root of 17836 is 135.55..., so the smaller factor is less than 135. The other factor is also in the form 4*7*k or 28k where k is a positive integer, because 4 and 7 are relatively prime. That means you have to only test the numbers 28, 56, 84 and 112.
The only number that even divides is 28, and the quotient is 637, which is divisble by 7. 637+28=665
Re: Modular Arithmetic
Posted:
Sat Apr 20, 2013 10:21 pmby sxk1693
Way to complicated. Just factor the numbers(in 89) and satisfy the constraints.
Re: Modular Arithmetic
Posted:
Mon Apr 22, 2013 1:15 pmby ZekeusAurelius
Sweet I like that solution, I feel dumb for not figuring that out before