Someone gives me 9900 dollars. Included in the 9900 is 5% is a goods
and services tax. What equation does one use to determine what isn't
tax? If I said that 9900 x 95% = 9405, that would be correct. However,
if I took that same number 9405 and multiplied it by 1.05 to reflect
the 5% tax, I get 9875.25 and not 9900.

Hi,

Am Fri, 5 Aug 2011 01:40:13 -0700 (PDT) schrieb rhhince:

Someone gives me 9900 dollars. Included in the 9900 is 5% is a goods
and services tax. What equation does one use to determine what isn't
tax? If I said that 9900 x 95% = 9405, that would be correct. However,
if I took that same number 9405 and multiplied it by 1.05 to reflect
the 5% tax, I get 9875.25 and not 9900.

your 9900 dollars are 105%.

9900/105*100 = 9428.57


Regards
Claus Busch
--
Win XP PRof SP2 / Vista Ultimate SP2
Office 2003 SP2 /2007 Ultimate SP2

"rhhince" wrote:
Someone gives me 9900 dollars. Included in the 9900 is 5% is a goods
and services tax. What equation does one use to determine what isn't
tax? If I said that 9900 x 95% = 9405, that would be correct. However,
if I took that same number 9405 and multiplied it by 1.05 to reflect
the 5% tax, I get 9875.25 and not 9900.

Ostensibly:

=9900/(1+5%)

Algebraically, the total cost was computed by:

totalCost = grossCost * (1+5%)

So, the gross cost is:

grossCost = totalCost / (1+5%)

Real-world considerations.... Really, the total cost is computed by:

=ROUND(grossCost*(1+5%),2)

So the gross cost should be computed by something like:

=ROUND(totalCost/(1+5%),2)

But that might off by 1 cent because we do not think we know whether to
round up or down.

rhhince,
1/.95 is not 1.05 but
1.0526315789473684210526315789474 (appx)

1.00/1.05= is not 95% but 95.23+%
(0.95238095238095238095238095238095)

1.0526315789473684210526315789474* $9405=
(Approximately) $9900

--
Rich/rerat
(RRR News) (message rule)
((Previous Text Snipped to Save Bandwidth When Appropriate))


"rhhince" wrote in message
...
Someone gives me 9900 dollars. Included in the 9900 is 5% is a goods
and services tax. What equation does one use to determine what isn't
tax? If I said that 9900 x 95% = 9405, that would be correct. However,
if I took that same number 9405 and multiplied it by 1.05 to reflect
the 5% tax, I get 9875.25 and not 9900.