This evening I had dinner with my husband's assistant of many years, Jill.  We had a lovely time catching up and she gave me a bag of personal items that were still at his office.  Among the items were two expired passports and three more HP calculators, pictured above.  He was never without a calculator in his pocket and between the office and home, we have now counted 7.  The passports expired in 1996 and 2006, so now we're on the hunt for the ones in between and see if there are others hiding here at the house.  Truly, the man never threw anything away.  
So it was a sweet remembrance, these old passports with stamps from the many countries he visited (and worked in) around the world.  One of his colleagues suggested we give one of his calculators to each grandchild.  Maybe.  But for now, I am keeping everything close to me.