Tarek wroteI saw few posts about the new sign up test and tried it myself ... this test is geared toward programmer , we should have another test for your everyday geek , maybe a small question about hex or binary ...something about hardware perhaps ?
No need for programming knowledge:
To find the sum of multiples of m (not 0) less or equal to n:
Let c = n mod m
S(m,n) = Sum for i=0 -> i=(n-c)/m of m*i
S(m,n) = m * Sum for i=0 -> i=(n-c)/m of i
S(m,n) = m * (n-c)/m * ((n-c)/m + 1) / 2
S(m,n) = (n-c) * (n-c+m) / 2 / m
The final result is S(m1,n) + S(m2,n) - S(m3,n) where m3 is the lcm of m1 and m2.
For more info you can refer to
http://lebgeeks.com/forums/viewtopic.php?pid=134266#p134266