rounding off. (1 Viewer)

[bby]

when a question asks
solve *insert question* and round off to the nearest.. errr... sig fig, or decimal place,
do u have to write the whole thing which is on the calculator first? or is it okay to just write (if its the final answer) the rounded value without doing so?

eg. solve *question* and round to 2 dp
0.22 (to 2dp)

some people tell me that you have to write.. like 0.22345643454 first and THEN 0.22 (to d.p) and some people tell me it isnt necessary. WHATS RIGHT? D:

 

[huhwotsthis]

It's not necessary, but it doesn't hurt.

I would do it like

0.22 (0.22345643454)

 

[youngminii]

Unnessecary, just write 0.22 (2dp).

 

[iSplicer]

when a question asks
solve *insert question* and round off to the nearest.. errr... sig fig, or decimal place,
do u have to write the whole thing which is on the calculator first? or is it okay to just write (if its the final answer) the rounded value without doing so?

eg. solve *question* and round to 2 dp
0.22 (to 2dp)

some people tell me that you have to write.. like 0.22345643454 first and THEN 0.22 (to d.p) and some people tell me it isnt necessary. WHATS RIGHT? D:

Just the rounded will do.

 

[iRuler]

Unnessecary, just write 0.22 (2dp).

this is what i've been told to do by teachers

 

[iSplicer]

It's not necessary, but it doesn't hurt.

I would do it like

0.22 (0.22345643454)

Thats worse, the one provided in brackets will only cause confusion

 

[huhwotsthis]

it wont if you're not retarded

 

[Drongoski]

it wont if you're not retarded

I always advise my students to write down the figures from the calculator to a few extra digits from the final reqd answer with ' . . . ' before giving the final answer; this way you show you understand what is reqd and where the final answer comes from.

e.g. calculator shows: area A = 37.526376956 and ur asked to give answer to 2 d.p. say:, you write:

A = 37.5263 . . . (altho you need not show the last '3')

= 37.53 (2 d.p.)

 

[0hNivlek]

^ i do that too!

 

[kwabon]

I always advise my students to write down the figures from the calculator to a few extra digits from the final reqd answer with ' . . . ' before giving the final answer; this way you show you understand what is reqd and where the final answer comes from.

e.g. calculator shows: area A = 37.526376956 and ur asked to give answer to 2 d.p. say:, you write:

A = 37.5263 . . . (altho you need not show the last '3')

= 37.53 (2 d.p.)

i do that as well

 

[addikaye03]

I always just write the d.p bit straight out, except when dealing with trig (e.g. @=0.327373929383, then i write @=32'45' ( to the nearest minuite) etc etc

 

[Fortify]

It's best to look at the numbers given in the question and see how many significant figures it has. Let's say the question says: "What is the concentration of a 25.00mL HCL which contains 0.0200moles?"

And say the answer is: 0.8molL^-1 but since the numbers in the question has 4 significant figures it is better to state: 0.800molL^-1.

 

[cutemouse]

I always advise my students to write down the figures from the calculator to a few extra digits from the final reqd answer with ' . . . ' before giving the final answer; this way you show you understand what is reqd and where the final answer comes from.

e.g. calculator shows: area A = 37.526376956 and ur asked to give answer to 2 d.p. say:, you write:

A = 37.5263 . . . (altho you need not show the last '3')

= 37.53 (2 d.p.)

That's for Maths, not Chemistry or Physics, or any HSC level sciences for that matter. Yet again you've been signature whoring to get people to sign up to your services by giving your absolutely rubbish advice. Stop it!

Now, you *should* round to the sig fig given in the question, but at HSC level I don't think they penalise you if you round to say 2 dp instead of 1 dp (like if they ask you to calculate the molar heat of a substance). Of course there are exceptions like no. of moles, and Quantum to Quarks in Physics but it's not that major, unless the question asks it.

 

[addikaye03]

It's best to look at the numbers given in the question and see how many significant figures it has. Let's say the question says: "What is the concentration of a 25.00mL HCL which contains 0.0200moles?"

And say the answer is: 0.8molL^-1 but since the numbers in the question has 4 significant figures it is better to state: 0.800molL^-1.

yer thats very true for chemistry and physics, this is also sometimes part of the marking scheme. I thought were talking maths specifically.