The Mathbird

I saw a mathbird in a tree.
That little mathbird sang to me,
“Twiddle-diddle-diddle-dee,
Little Sarah’s 2 + 3.”

Or did it whistle 3 +2?
I’m not quite sure. I wish I knew.
It sang just once then it was through.
It sang just once and off it flew.

When it flew back, it sang once more
And what it sang I can’t ignore.
It told me Sarah’s birthday score
Is 4+1…or 1 +4.

I do not know, sweet birthday hero.
Perhaps it whistled 5 + 0?
Or could it be, now, sakes alive,
It first sang 0, then sang 5?

I cannot guess. I do not dare.
I do not know. I do not care.
I add them up. I add them down,
And inside out and all around.

How old you are, I cannot say.
And now that mathbird's gone away.
I cannot figure out its clue,
So Sarah, please, how old are you?