ICICI Salami Slicing?

pthompson

Does anyone else have a strange balance on their account like this:

[HTML]Date Description Credit Debit Balance(GBP)
23/08/2005 TFR0123456789 99.00 - 99.9999999999991
09/08/2005 CHEQUE DEPOSIT 1.00 - 0.999999999999091[/HTML]

I know it's just a fraction of a penny, but I'm curious about where the rest of my £1 went to.

Am I just being paranoid, or have I uncovered a "salami slicing" scandal ( http://www.mnin.org/?page=salami&left=off )?

I've asked ICICI for comment, but am still waiting . . .

- Paul.

Stonk

Computers don't store numbers with absolute precision (even numbers that you would think could be expressed precisely like 100.000000000, because computers work in binary not decimal), so you often find outputs from computers like this. 7 or 15 significant figures are common, and it looks like we've got 15 here - suggesting that they're using 64-bit floating point numbers. Usually the software is written properly enough to round to 2 decimal places before displaying to the user though!

masonic

pthompson wrote:

...I know it's just a fraction of a penny, but I'm curious about where the rest of my £1 went to...

I think I have it:-

[HTML]Date Description Credit Debit Balance(GBP)
03/07/2005 TRANSFER 9.00 - 10.0000000000005
28/06/2005 CHEQUE DEPOSIT 1.00 - 1.00000000000045
[/HTML]

pthompson

masonic wrote:

I think I have it:-

[HTML]Date Description Credit Debit Balance(GBP)
03/07/2005 TRANSFER 9.00 - 10.0000000000005
28/06/2005 CHEQUE DEPOSIT 1.00 - 1.00000000000045
[/HTML]

:-) How about sending me a cheque for that surplus amount?

pthompson

Stonk wrote:

Computers don't store numbers with absolute precision ... so you often find outputs from computers like this.

Your explanation sounds plausible, Stonk, but I still don't see why my £1 got stored differently to Masonic's (0.999999999999091 compared with 1.00000000000045).

Maybe his was a Scottish £1? ;-)

masonic

pthompson wrote:

:-) How about sending me a cheque for that surplus amount?

Would love to, but think I'm unpopular enough with my bank manager already! :rotfl: