Well because EUO doesn't have a real "value" for null since it deals with variable arguments mostly like strings unless math can be done. At least with stronger typed languages, you can divine what the value should be, but you can't make the assumption with a language like EasyUO. But if you can actually setup what you'd like "null" to be, then you get your <3 of nulls and you can talk about empty strings, zeros, N/A, etc.
Actually, if you try and do any math to a N/A, it's treated like a zero. Also if the value that's found in a variable doesn't actually represent a number, then it's considered a zero or N/A.
set %test imanumber
set %test %test * 5 + 10
display ok %test
This will result in a 10 since the multiplication evaluates to zero.