1 {A post-it note, with the following items written on it in an old-fashioned cursive hand:}
1 [note]: - Milk
1 [note]: - Bread
1 [note]: - Eggs
1 [note]: - Toilet Paper
1 [note]: - Flowers for Mrs Fermat
1 [note]: - Pay Phone Bill
1 [note]: - Write out that Proof
1 [note]: - Cat Litter - URGENT!
1 [note]: - More Post-Its
1 [note]: - Writing Paper
1 {in the top right of the note, with an arrow pointing at the last two items in the list} why is there never anything to write on around here??
1 {bottom right, squeezed in the remaining space in tiny script} I found an odd perfect number but it's too long to write here

And here we have Fermat's Last Post-it.

I've talked about Fermat's Last Theorem before, so al I need to do here is provide the appropriate link.

---

2020-02-16 Rerun commentary: Looking at this again, I had no idea if Pierre de Fermat was even married, and thus might need to buy flowers for Mrs Fermat. (I suppose the flowers could have been for his mother, but I prefer the thought that he was writing it in this list for his wife, if he had one).

I thought Wikipedia would provide the answer, but alas its article on Fermat is (as of this writing) utterly silent about the topic of whether he was married or not. Which seems an odd oversight for an article about such a prominent person - if the facts are known.

A quick bit of searching found several articles, each of which contains a subset of details about Fermat's private life. Putting it all together, it seems that on the date 1 June, 1631, at the age of 23, Fermat married one Louise de Long, who was a fourth cousin of his mother Claire de Fermat (née de Long), making her Fermat's fourth cousin once removed. Louise was 15 years old at the time of the marriage, turning 16 a month later. The couple had eight children, five of whom survived to adulthood: two sons, Clément-Samuel and Jean, and three daughters, Claire, Catherine, and Louise.

According to one genealogy site, Louise (Fermat's wife, not the daughter of the same name) lived until at least 1690, outliving Fermat (who dies in 1665) by at least 25 years.

Now, if anyone would like to do the research and tell me if Mr and Mrs Fermat in fact owned a cat, I would be most grateful.