Ever found yourself dispensing training when you assumed surely none was needed?
Passing through our office enroute to somewhere else, I noticed a user adding up columns in excel line by line with a calculator and typing the totals at the bottom..
Unable to stand watching this, I educated the user on how =sum worked in Excel, which was met with total amazement and a comment that all he then had to do was add the VAT etc. I promptly did another column with=sum(cell*$vat) calculating the VAT and then another one with the totals, with a grand total at the bottom, and I saved a blank template for him.
Apparently, this was passed around the team and saved a unbelievably absurd number of hours work adding everything up manually, then having it checked by different people and signed off before being passed to the accounts department who then did their own checks because errors were still slipping through.