Hmm. It should not be incorrect to throw the extra mā in there. I learned numbers without the extra mā, just as DL has it here. Eleven was 'uimikumakahi. Apparently, my interpretation of eleven was either 1) a new 1980's way of expressing numbers or 2) a specific dialect.
Traditionally, (as the story goes) the extra mā was always included in numbers. I was told that either one was "toe-mah-toe" or "toe-may-toe."