Reindeer Named Remainder

A reindeer named Remainder,
Followed me one day,
Rita, I renamed it,
Renamed it right away!
  Rita-Pita sis' said,
“Cause sis’ was half of ten,
And I was twice her age,
At least I was back then!
My reindeer named Remainder,
She was great at math,
Addition right through algebra,
And graphing on a graph...
But when she tried division,
 Things would go astray,
She made a bad decision,
Is what I have to say,
 Each time she found a quotient,
Her mind went out to sea,
She added a remainder
Where remainders shouldn’t be...