When I was working in the National Commercial Bank, Amsterdam, we were taught to reconcile accounts, e.g. comparing our own account statement of a corresponding bank with that mailed to us by the correspondent.
Often, the totals would differ, strangely, by a number divisible by 9.
For example, our total might be $ 56,023.00 and theirs $ 56,068.00,
with a resulting difference of $ 45.00.
This is caused by a simple "twister", for example when a typist entered
$ 16 instead of $ 61 or
$ 27 instead of $ 72 or
$ 38 instead of $ 83 or
$ 49 instead of $ 94 or
$ 50 instead of $ 05 . . .
NOTE: the possibilities always occur in sets of 5 as above.
I also noted that these plurals of 9 can quickly been computed
by taking the difference between the two digits and multiplying that by 9.
For example, the number 38 will be associated with a twister of (8 - 3)* 9=45
Check out: 38 and 83 differ by 45.
After a while, it becomes fairly easy to spot the error -
that is, as long as there's only a single error.
BLO fecit 20040827 -