Also, the order of the numbers is the opposite: "dwa i cztery", and not "cztery i dwa".
As far as I know, and I studied mathematics in English, the syntax is:
"Two and four equals six" or "Two and four is equal to six."
The same pertains to the total or the sum of the two:
"The total of two and six equals six." or "The total of two and four is equal to six."