Ze Values? HELP

[PEG]

...This is why that Mars lander bounced off in to the yonder....

"By calculation", 0.8 x 0.320 = 0.256 not 0.3

By restraint of scale,rounding down etc,yes,but NOT by calculation,which by its' description,is definitive.

0.8 x 10 to the -6 is 0.0000008 or 8 to the -7 , the power of -6 being a millionth,micro or multiple of 0.000001.

...And,as my maths teacher was inclined to ask,after a grueling,set of calcs,"We know friction makes heat?...and heat boils water?...So how long will it take a donkey to ---- a bucket of water,so we can have a cup of tea?" :icon12:

 

[telectrix]

...This is why that Mars lander bounced off in to the yonder....

"By calculation", 0.8 x 0.320 = 0.256 not 0.3

By restraint of scale,rounding down etc,yes,but NOT by calculation,which by its' description,is definitive.

0.8 x 10 to the -6 is 0.0000008 or 8 to the -7 , the power of -6 being a millionth,micro or multiple of 0.000001.

...And,as my maths teacher was inclined to ask,after a grueling,set of calcs,"We know friction makes heat?...and heat boils water?...So how long will it take a donkey to ---- a bucket of water,so we can have a cup of tea?" :icon12:

about 15 minutes if the donkey's on ------,

 

[davesparks]

...This is why that Mars lander bounced off in to the yonder....

"By calculation", 0.8 x 0.320 = 0.256 not 0.3
:

Ok I should have said 0.8ohms x 0.320 =0.256

In any scientific calculation an answer cannot be more accurate than the least accurate input value.

 

[Paul.M]

I would not drink it though

 

[HandySparks]

Ok I should have said 0.8ohms x 0.320 =0.256

In any scientific calculation an answer cannot be more accurate than the least accurate input value.

Indeed, but you shouldn't make any assumptions about accuracy based only on the number of decimal places or significant figures used.

See my post here: http://www.electriciansforums.co.uk...0424-three-phase-calculation.html#post1079853

My multimeter shows values to 4 significant figures. Can I assume that it's accurate to plus/minus half of the final digit? No! But I still might write down the value I see on the display.

Here's another (silly) example: Would a shop selling something for £1.49 accept a "one pound" coin (0 decimal places), since it's not labelled as a "£1.00" coin?

 

[Deleted member 72666]

Hi,dude, You will have to grow a sense of humour,as you have only had 20% of the 100% normally given,which is,after all,only one seventh....:conehead:

But is that higher or lower than 100%?

 

[davesparks]

Indeed, but you shouldn't make any assumptions about accuracy based only on the number of decimal places or significant figures used.

See my post here: http://www.electriciansforums.co.uk...0424-three-phase-calculation.html#post1079853

My multimeter shows values to 4 significant figures. Can I assume that it's accurate to plus/minus half of the final digit? No! But I still might write down the value I see on the display.

Here's another (silly) example: Would a shop selling something for £1.49 accept a "one pound" coin (0 decimal places), since it's not labelled as a "£1.00" coin?

Around about now my dear old physics teacher would be tearing a few strips off you!

 

[newtothis]

The zero is relevant to the outcome of the calculation as it will have an impact on its accuracy.
0.8 x 0.320 = 0.3
0.80 x 0.320 = 0.26
0.800 x 0.320 = 0.256

0.8 is a value anywhere between 0.75 and 0.84 wheras 0.80 is a value between 0.795 and 0.804

Thanks for replying - it's appreciated, I'm a bit confused cos my calcs show the number of zeros is irrelevant.
I suspect it's expressed as 0.8 because that's what it is. If it was 0.802 then this would have to be noted
that 0.8 is correct to x decimal places. ??

0.8x 0.320 = 0.256
0.80=0.320 = 0.256
0800x0.320 = 0.256