IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: @d!_†oX!© on October 26, 2009, 09:18:14 am

Title: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 09:18:14 am
if the number given to us is ,for ex., 0.051939582
now v have to write it correct to 3 significant figures
so will the answer be 0.052 or 0.0519

basically my question is that is the zero after the decimal counted if written b4 another number...???
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 09:21:31 am
yea its ryt...

@adi_toxic
yes after decimal, 0 does count in significant figures.
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 09:30:18 am
okiee :)
Thanks guys
just wanted to confirm!! :P
Title: Re: IGCSE MATHS
Post by: Tiryan on October 26, 2009, 10:14:01 am
Isn't a significant figure the first non-zero number ? So 3 significant figures would be 0.0519
Title: Re: IGCSE MATHS
Post by: astarmathsandphysics on October 26, 2009, 10:23:34 am
Exactly right tiryan 0.519
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 10:24:23 am
i that the right as astar???
m confused...
som1 is saying 0.052 nd som1 is saying 0.0159
wt do i do????
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 10:25:27 am
Isn't a significant figure the first non-zero number ? So 3 significant figures would be 0.0519
no..becz after decimal 0 does hold significance.
so itll be 0.052 only (doesnt matter if u or dont write the 0 before decimal pt.)
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 10:27:02 am
Exactly right tiryan 0.519
its 0.052
guess u missed the zero after decimal!
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 10:29:12 am
but astar and tiryan say it shud be 0.0159
Title: Re: IGCSE MATHS
Post by: adorabledaughter_07 on October 26, 2009, 10:31:09 am
u want it to 3 sig figurs rite?...so 0.0159 is rite...nd 1 mor thing...0 does count after decimal only if there is a numbr be4 de decimal
Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 10:33:25 am
nono..i'm sry...its 0.0159

Zeros at the beginning of a number are not significant. For example, 0.002 has one significant figure while 0.0045 has two significant figures.
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 10:36:45 am
ooops...kz guys!
me was rong :-[


here it is..
Leading zeros are not significant. For example, 0.00052 has two significant figures: 5 and 2.
-frm google..
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 10:39:49 am
so finally it is 0.0519 rite????!!!!
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 10:42:33 am
yes adi_t


here...
The rules for identifying significant digits when writing or interpreting numbers are as follows:
>All non-zero digits are considered significant. Example: the number 1 has one significant figure. In 20 and 300, the first figure is significant while the others may or may not be (see below). 123.45 has five significant figures: 1, 2, 3, 4 and 5.
 
>Zeros appearing anywhere between two non-zero digits are significant. Example: 101.12 has five significant figures: 1, 0, 1, 1 and 2.
 
>Leading zeros are not significant. For example, 0.00052 has two significant figures: 5 and 2.

>Trailing zeros in a number containing a decimal point are significant. For example, 12.2300 has six significant figures: 1, 2, 2, 3, 0 and 0. The number 0.000122300 still has only six significant figures (the zeros before the 1 are not significant). In addition, 120.00 has five significant figures. This convention clarifies the precision of such numbers; for example, if a result accurate to four decimal places is given as 12.23 then it might be understood that only two decimal places of accuracy are available. Stating the result as 12.2300 makes clear that it is accurate to four decimal places.
Title: Re: IGCSE MATHS
Post by: adorabledaughter_07 on October 26, 2009, 10:46:32 am
120.00..u sur it haz 5 sig figurez?
Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 10:49:06 am
120.00..u sur it haz 5 sig figurez?

i dont think it is..but its from wikipedia.
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 10:56:51 am
i dont think it is..but its from wikipedia.

i chked it with two more sites n it says the same..

Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 10:59:36 am
guys it is 0.0159
as in the preceeding zero is not counted as per our own mark schemes...
i think dts enough for the confirmation
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 11:03:39 am
Zeroes placed after other digits but behind a decimal point are significant; 7.90 has three significant digits.

Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 11:08:24 am
Zeroes placed after other digits but behind a decimal point are significant; 7.90 has three significant digits.



this cant be true

7.90 can be written as 7.900000000 or 7.9

its all the same...this changes the no. of significant digits..u sure abt this?
Title: Re: IGCSE MATHS
Post by: adorabledaughter_07 on October 26, 2009, 11:12:16 am
yehz sme q...soh u mean 120.000 has 6 sig figurz...nd 120.0000 haz 7???
Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 11:13:31 am
yehz sme q...soh u mean 120.000 has 6 sig figurz...nd 120.0000 haz 7???

how many wil 120.0000000000000000000000000000000000000000000000000000000000000 have?

lol ... :P :P
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 11:16:48 am
this cant be true

7.90 can be written as 7.900000000 or 7.9

its all the same...this changes the no. of significant digits..u sure abt this?
okay...im realli confused now.. ???
i think we must wait for astar?
need explanation because i chked this thing with few sites n they say this only :-\
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 11:19:06 am
guys its very simple..
v count zero as a significant figure only if it comes between to no. dt are nt 0
dt means:
0.012 has 2 sig figs
0.120 has 2 sig figs
0.102 has 3 sig figs
Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 11:22:06 am
guys its very simple..
v count zero as a significant figure only if it comes between to no. dt are nt 0
dt means:
0.012 has 2 sig figs
0.120 has 2 sig figs
0.102 has 3 sig figs

we all know that adi..check wat Z.J type ...that was from wikipedia...read the whole thing..
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 11:29:23 am
but i dont agree with it!!!!!!
u
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 11:36:27 am
wait for astar!
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 11:37:02 am
ya ok...bt wen will he be back???
Title: Re: IGCSE MATHS
Post by: sameer210394 on October 26, 2009, 11:54:24 am
yes adi_t


here...
The rules for identifying significant digits when writing or interpreting numbers are as follows:
>All non-zero digits are considered significant. Example: the number 1 has one significant figure. In 20 and 300, the first figure is significant while the others may or may not be (see below). 123.45 has five significant figures: 1, 2, 3, 4 and 5.
 
>Zeros appearing anywhere between two non-zero digits are significant. Example: 101.12 has five significant figures: 1, 0, 1, 1 and 2.
 
>Leading zeros are not significant. For example, 0.00052 has two significant figures: 5 and 2.

>Trailing zeros in a number containing a decimal point are significant. For example, 12.2300 has six significant figures: 1, 2, 2, 3, 0 and 0. The number 0.000122300 still has only six significant figures (the zeros before the 1 are not significant). In addition, 120.00 has five significant figures. This convention clarifies the precision of such numbers; for example, if a result accurate to four decimal places is given as 12.23 then it might be understood that only two decimal places of accuracy are available. Stating the result as 12.2300 makes clear that it is accurate to four decimal places.

this is absolutely right...

this para explains it all.. wat all explanation du u guys need ???
Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 11:56:29 am
does 120.00 have 5 significant digits?

its written in the para..
Title: Re: IGCSE MATHS
Post by: Tiryan on October 26, 2009, 12:04:19 pm
does 120.00 have 5 significant digits?

its written in the para..

No 120.00 does not have 5 sig figs, cause that can be written a million other ways.

The only time you count a zero after a non-zero number is if it has another non zero number after (the zero).

Thats going to throw off a few more ppl :D
Title: Re: IGCSE MATHS
Post by: Ghost Of Highbury on October 26, 2009, 12:14:41 pm
No 120.00 does not have 5 sig figs, cause that can be written a million other ways.

The only time you count a zero after a non-zero number is if it has another non zero number after (the zero).

Thats going to throw off a few more ppl :D

thats exactly wat i said..

my point is "WIKIPEDIA" says so... have a look at what Z.J posted..
Title: Re: IGCSE MATHS
Post by: @d!_†oX!© on October 26, 2009, 12:17:54 pm
WHERE IS ASTAR????????
Title: Re: IGCSE MATHS
Post by: astarmathsandphysics on October 26, 2009, 12:37:44 pm
I am here.
Title: Re: IGCSE MATHS
Post by: astarmathsandphysics on October 26, 2009, 12:38:26 pm
does 120.00 have 5 significant digits?

its written in the para..

yes it does
Title: Re: IGCSE MATHS
Post by: astarmathsandphysics on October 26, 2009, 12:39:56 pm
120 can be eoither 2 or three sig figs but 120.00 is def 3 sig figs cos the zeroes are after the decimal point
Title: Re: IGCSE MATHS
Post by: astarmathsandphysics on October 26, 2009, 12:41:58 pm
zeros after a number which is after a decimal point count as sig figs
to 3 sig figs 0.01000001 is written 0.0100
Title: Re: IGCSE MATHS
Post by: zara on October 26, 2009, 12:44:09 pm
alyt!

i get it now...Thanks..