Follow procedure half the time? in Developer Help
Modulus! <dm> for(var/n in 1 to 10) if(!(n % 2)) world << n
Check the DM Reference entry for the % operator. It simply gives the remainder of A divided by B. In the example I provided, it checks if A%B is 0, which is the case in even numbers divided by 2.
Name a single even number that, divided by 2, leaves a remainder that is not 0.
<dm>
for(var/n in 1 to 10)
if(!(n % 2))
world << n