Oldest Working AA Battery?

[BogStandard]

Back in around 1983 I bought a calculator for my daughter as she was starting Secondary School.
I still have it in a draw but it has rarely been used in the past 40 years. Yesterday I turned it on a couple of times and it powered up although only for a short while. I had no recollection of ever changing the batteries so opened the battery compartment and saw they were the original batteries dated 83-06. They had not leaked in all this time although the contacts look a little corroded. I spun the batteries in-situ to freshen the contact points and it worked!
I have attempted to attach images but my earlier failed trial attempts mean I have exceeded an 8Mb quota.
The batteries are branded Casio in white lettering on a blue background.

Regards…