A Poem of Threes

I really love the number three,
So when I store my books, you see:
(Now pay attention to these facts)
I pile them all in 3-high stacks.
My books (now, don’t be terrified)
Are all in 3 rooms side-by-side;
The count per room (don’t be perplexed)
Is triple, one room to the next.
At 40 books, I bought some more
But never reached one hundred four.
So now deduce (oh, please don’t groan)
How many books I claim I own.