I love when a tip for a good book comes from such a random source as this one did. I was reading the website Quora, and the book "The Housekeeper and the Professor" was recommended in the comments to the answer to a question.
This is the story of a Japanese housekeeper and single mother who starts to take care of a 64 year old mathematics professor who was long ago injured in a car accident. As a result his memory lasts only 80 minutes, and although he can remember his past up to then, he can no longer form new memories.
The agency our housekeeper narrator works for has already sent 8 people before her to care for him, so no doubt there are difficulties. She is hard working and adaptable however, and receptive to him as he communicates in the only way he knows; via the timeless language of mathematics. When meeting someone for the first time (which may not really be the first time at all for them), he will ask for their birthday and find interesting properties of that number. For example the housekeepers birthday is 2nd Feb, 222, which forms an amicable number with 284, the serial number of his watch.
Maintaining some rudimentary form of long term memory via post-it notes on his suit, he remembers the housekeeper by a simple doodle, and that she has a son. He has a note prominently located to remind him "you have only 80 minutes of memory".
Soon he discovers that her son is a latch key kid, and tells her to bring him with her in future, and so she does. The professor loves children and his relationship with her son, who he calls root because his head looks like the square root symbol, is very warm and endearing.
The book reminds me of a sort of mathematics imbued version of Nick Hornby's Fever Pitch, because the characters connect through the sport of Baseball, just as in the latter they connect over soccer. This all starts when the housekeeper finds a box of baseball cards in the professors cupboard.
Yoko Ogawa, the author, is knowledgable and able pass on her knowledge and passion for mathematics and numbers to the reade. The whole book is about finding ways to connect with people, about the joy and timelessness of numbers and their properties. Despite being a translation from Japanese to English, there's no mistaking the truth and warmth of this story.
In case it's not clear, highly recommended.