Pick up a calculator - that archaic piece of office kit still found in every accounts department - and you will find it has a bog-standard, everyday function that Excel developers still can't be bothered to make available to the millions of accountants out there who have loyally used their program, day in, day out, for the past 20 years.
I'm not talking about a super 'scientific' calculator, either - the kind banned in maths O Level (for those of us who remember them). Just an ordinary one.
Have you found the answer? It's the +/button, the one that simply reverses the sign with one stroke.
It's not rocket science. I think I probably first used that button at the age of about seven, between attempts to write the word 'goggles' upside down (you can do it by typing 5376606, for those who want to try it at home).
If you want to reverse the sign of a patch of Excel, you have to multiply all cells by minus one or set up a macro. It's crazy, and it still requires "Custom Formatting" to get negative figures into brackets.
It's like going back to accounting in the Middle Ages. Do the Excel development team still tip the contents of their chamber pots of out the window, or do they perhaps have indoor plumbing?
Microsoft Excel continues to dominate the lives of finance directors.
In this age of 'leaner and meaner' technology, isn't it about time that accountants organised a protest to rage against the Microsoft machine? (Although I do wonder what that would look like.)
Why has nothing come along to replace it, stealing its best ideas and dazzling us with new functions?
Why haven't we got moving graphics and magic icons that can transfer workbooks into a jazzy PowerPoint presentation at the click of a button?
I am a hypocrite, though. I complain about Excel, but I use it for everything. My love affair with it reached new heights in 2012 when I decided I would transfer my 'to-do' list into it as well - all 60 tasks colour-coded, scheduled and cross-referenced week by week for each of the next 52 weeks.
It almost surpasses (but not quite) my home-decorating planner, complete with to-scale diagrams of every wall of our house, square metreage notes and the paint requirement of each individually calculated.
Nor does it quite equal my recipe database, which allows me to filter down to a shortlist of recipe plans, based on the ingredients I have in the fridge on any particular day.
At the same time, however much Excel has been a valued tool, we all also like innovation and jazzy new takes on old ways of doing things. Twenty years of cashflow documents in Excel, management accounts in Excel, KPI reports in Excel and it could start to get pretty repetitive.
The truth is, Excel isn't perfect - it's just the best we have available. And I really don't think that we finance directors want to be here in 20 years' time, using Excel to wake us up in the morning.
We want to be dazzled.
Helen Simmons is finance director at the Diocese of London