These sorts of errors are frequent and pervasive in finance. Not just numbers. I worked on a ref dare system with minimal input validation. Copy/pastes would l

These sorts of errors are frequent and pervasive in finance. Not just numbers. I worked on a ref dare system with minimal input validation. Copy/pastes would leave in white spaces, new lines, etc. This would then break trading which tried to execute them. Aged 17/18 at a summer work program at a fund (~2000) I was given Excel and Bloomberg and had to calculate risk across client portfolios. Messed up the manual input of one by a zero resulting in the whole portfolio getting rebalanced, then un-rebalanced. The same team passed off a trade via paper slip saying it’s yen. The person entering it didn’t recognize the yen currency symbol, assumed it was a 7 and traded the full number prefixed with 7 in yen instead. Many many stories of many many errors.