In the money!

I received a cheque in the post this week - £25!  This is 'found money' because I wasn't expecting it and hadn't budgetted for the windfall.  As I said a couple of days ago, I'm bound for England to see the extended family, so I've said 'the drinks are on me'  I hope there aren't too many in the pub next week or I'll regret not saying 'the Milky Bars are on me' instead.  I've used that phrase in its literal sense several times in my long and varied teaching career, when I've asked the students to teach each other, by researching and preparing presentations, and give me a bit of a breather.

ANNyway, the cheque: it came from Blackpool as a pay-out from the £50 in premium bonds that was given to me by a rich(ish) aunt for my 8th birthday in 1962.  It's my second 'win'.  When PAYOLA last rang in about 1976, I calculated that the return on investment was almost exactly what I would have gotten if I'd invested the £50 at interest.

So I thought I'd do that again.  The most excellent and informative Guardian Datablog had a report on interest rates since 1694 from which I was able to calculate (with my since-January acquired ExCel skills) the MAX (17%), MIN (0.5%) and AVERAGE (7.52%) interest rates since Jun 1962.  So I estimate that £50 invested at appropriate interest rates compounded over half a century is ... [paste 50*1.0752^50 into WolframAlpha] ... £1877!
which I've written in a large font because it's rather bigger than the £50 that I've actually had returned by the British Gumment.