I can count to potato

Have you ever heard the rhyme:
One potato, two potato, three potato, four.
Five potato, six potato, seven potato, more.
I have a calculator that counts potatoes.
It only goes to seven.
Anything above seven, it just says “more.”
Which is just shorthand for “more than seven.”
Just like “four” is shorthand for “four potatoes.”
The calculator only works with potatoes.
If you try to count anything else on it, it just sits there.
It only counts whole potatoes. No mashed potatoes, fried potatoes, or Mister Potato Heads.
I got it as a gift.
I should sell it on eBay.