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Thread ID: 112882 2010-09-25 21:14:00 Net of GST Bryan (147) PC World Chat
Post ID Timestamp Content User
1139609 2010-09-26 01:08:00 ...don't ask me why...
The reason is because in the first instance, you're adding 15% of 100 (i.e. 15), and in the second instance you're subtracting 15% of 115 (i.e. 17.25). As 15% of 115 isn't the same thing as 15% of 100, that's what causes the incorrect answer. This is the same thing that Snorkbox was pointing out before.
Erayd (23)
1139610 2010-09-26 01:15:00 As 15% of 115 isn't the same thing as 15% of 100, that's what causes the incorrect answer.

Don't you mean, correct answer? (your example is correct - that 15% of 100 is not the same as 15% 0f 115)
WalOne (4202)
1139611 2010-09-26 01:15:00 I was just pointing out that pctek was wrong :2cents:

Ken
kenj (9738)
1139612 2010-09-26 01:17:00 Don't you mean, correct answer? (your example is correct - that 15% of 100 is not the same as 15% 0f 115)Touche... mathematically correct, but incorrect as a GST calculation. Erayd (23)
1139613 2010-09-26 01:40:00 7.66666666 You need 8 6's to get the required precision.
I found it to be 7.66666666666 which is 11 6's. That takes it to a decimal precision of 10. For most occasions 8 would be enough but over time those extra three would make a difference.
My reason for knowing that figure is so that I don't have to change a program I wrote ages ago as a calculator with specific GST that would stay on top of all other windows. My brother finds it very useful.
mikebartnz (21)
1139614 2010-09-26 03:18:00 Oh boy! What does this say about the standard of math education in NZ!!

Nothing wrong with my math education but it's a case of if you don't use it you lose it. :rolleyes:

After reading all this it seems to me that the IRD method is the easiest after all.
FoxyMX (5)
1139615 2010-09-26 08:49:00 The reason is because in the first instance, you're adding 15% of 100 (i.e. 15), and in the second instance you're subtracting 15% of 115 (i.e. 17.25). As 15% of 115 isn't the same thing as 15% of 100, that's what causes the incorrect answer. This is the same thing that Snorkbox was pointing out before.

Thanks for that, I have never been good with maths. When I went to school, it wasn't considered important for girls to learn it much. :blush:

LL
lakewoodlady (103)
1139616 2010-09-26 09:41:00 Should we just round it up and make GST 20% :p pine-o-cleen (2955)
1139617 2010-09-26 11:00:00 Should we just round it up and make GST 20% :p

Or down to 10%!
beeswax34 (63)
1139618 2010-09-26 20:46:00 Just use Xero, it takes care of it all, and always quote +GST ;) Chilling_Silence (9)
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