Why Is It ‘Eleven, Twelve’ Instead of ‘Oneteen, Twoteen’?

(via Mental Floss)  English number words are pretty logical after a point. From twenty-one to ninety-nine, the same principle applies: you say the tens place followed by the units place. But the teens are different. Not only does the ten come after the units place (10+7 is not teen-seven but seventeen), eleven and twelve don’t fit in at all.