Decimal places??

aimsirbia

Hi everyone

I'm trying to get the answer for someone preparing for a drugs calculations test but who isn't on this forum, advice appreciated m

I would be grateful if u can clarify whether: to round a figure to "1" decimal place for example is the same as writing a figure to one decimal place?


Convert 58922.76 mg to g (to nearest 2 decimal places eg 1.11 g)
Answer:58.92

So - if the question had been round to a 2 decimal place, the answer would be the same ya?

Thanks

Yakuza

To round to 2 d.p., you look at the 3rd digit after the decimal; if 5 or higher, round up else round down.

In this case, to round 58.92276g ,the 3rd digit after the dp is 2, so the .92 stays as is (58.92 as you state).

I read "writing a figure to one decimal place" as a form of truncation of the data (i.e. no rounding is performed, the digits after position 1 after the decimal are simply ignored) as opposed to rounding which uses the next digit along to see if the figure should be increased or decreased.

MathsManiac

Yakuza wrote: »

I read "writing a figure to one decimal place" as a form of truncation of the data (i.e. no rounding is performed, the digits after position 1 after the decimal are simply ignored) as opposed to rounding which uses the next digit along to see if the figure should be increased or decreased.

I would disagree. "Round your answer to one decimal place", "Write your answer correct to one decimal place", "Write your answer to one decimal place," all mean the same thing - all require rounding properly by inspecting the following digit.

Unless you're explicitly told to "round down", "round up" or "truncate", you should round "to the nearest", which gives the closest possible approximation to the true answer, subject to the specified constraint.

TheBody

MathsManiac wrote: »

I would disagree. "Round your answer to one decimal place", "Write your answer correct to one decimal place", "Write your answer to one decimal place," all mean the same thing - all require rounding properly by inspecting the following digit.

Unless you're explicitly told to "round down", "round up" or "truncate", you should round "to the nearest", which gives the closest possible approximation to the true answer, subject to the specified constraint.

+1 to this interpretation.

Michael Collins

MathsManiac wrote: »

I would disagree. "Round your answer to one decimal place", "Write your answer correct to one decimal place", "Write your answer to one decimal place," all mean the same thing - all require rounding properly by inspecting the following digit.

Unless you're explicitly told to "round down", "round up" or "truncate", you should round "to the nearest", which gives the closest possible approximation to the true answer, subject to the specified constraint.

I'd have to agree with this too, you're rounding either way, so might as well minimise the error unless you are told explicitly to truncate.

Also aimsirbia, don't fall into the 'rounding by rolling trap'. Which I thought was the correct way until disturbingly recently, when I figured it out independently of seamus' post, yet I distinctly remember being taught that way!

Yakuza

Fair enough, I bow to your collective wisdom It's not a phrase I'd use or hear, something in it struck be as being less precise as other ways of asking. Put it down to the three o'clock slump. In the staid world of insurance and IT where I work, technical specs are quite specific as to how many decimal places to display and round to, so I guess I'm used to seeing precise phrasing of a requirement. Personally I would always round to the nearest when stating a figure, I just thought (albeit in a low-sugar, decaffeinated state) that the OP's phrase implied truncation.