How do I change odd numbers to even numbers?

 

My lotsize calculation on a mini account might result in an 2-decimal double odd number such as .67 or 2.51.

How would I determine if the number is odd and change it down to the nearest even number (such as .66 and 2.50)?

 
The easiest solution is to use NormalizeDouble() to round the lot size to required precision. A better solution would be to use MathMod() in tandem with MarketInfo( Symbol(), MODE_LOTSTEP ). Whichever makes more sense in your situation.