Find the sum of all integers between 1 and 9999 that are divisible by 5 but not by 6 nor 7.

Any help is greatly appreciated!

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- May 10th 2005, 09:10 PMmathsmadPlease help
Find the sum of all integers between 1 and 9999 that are divisible by 5 but not by 6 nor 7.

Any help is greatly appreciated! - May 10th 2005, 11:04 PMpaultwang
Answer is 7137125

Matlab code:

a = 0;

for i = 1:9999

if mod(i,5) == 0 && mod(i,6) ~= 0 && mod(i,7) ~= 0

a = a + i;

end

end

disp(a); - May 18th 2005, 09:53 PMmathsmad
Is there a way of not using a calculater to work this out, in a logic way, by not also writing all the numbers out.

- May 24th 2005, 08:57 PMmathsmadQuote:

Originally Posted by**paultwang**

Reply With Quote - May 25th 2005, 08:15 AMpaultwang
> 9999/5.;

1999.8

> 9999/30.;

333.3000000

> 9999/35.;

285.6857143

> 9999/210.;

47.61428571

> 1999*(1+1999)/2*5;

9995000

> 333*334/2*30;

1668330

> 285*286/2*35;

1426425

> 47*48/2*210;

236880

> 9995000-1668330-1426425+236880;

7137125

Thanks buggler@Undernet for the help on this method. - May 28th 2005, 02:04 PMmathsmadThanks for the help
Thanks for the help