How to do suming up of difference of odd/even numbers?
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Usually when we have a series of numbers (let's say n = 1 to 30), we use this formula to sum up the difference from 16 to 30:
= (30+29+28+...+16)
= {[n(n+1)/2] - [(n/2)(n/2+1)/2]} = {[30x31/2 - 15x16/2]} = 345
What happen if we want to find for odd number series or even number series? can someone provide me formula? -
Normally I use excel to do such trivial things.
If you can see it, you can solve it.
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57 SUM 58 SUM
59 900 60 930 -
exam cannot bring laptop in leh...
then the tutor said i should learn tis kind of geomatic series in jc, the problem is i'm not from jc.
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Wah lau eh, you triple E leh, geometric series to you should be like sneezing or having sex. Pls don't push the blame to the jc poly divide.Originally posted by 798:exam cannot bring laptop in leh...
then the tutor said i should learn tis kind of geomatic series in jc, the problem is i'm not from jc. -
LOL... you know arithmetic series, don't know geometric series?Originally posted by 798:exam cannot bring laptop in leh...
then the tutor said i should learn tis kind of geomatic series in jc, the problem is i'm not from jc. -
Joker right?Originally posted by ndmmxiaomayi:LOL... you know arithmetic series, don't know geometric series? -
i only know how to masturbate. stop mocking at me n teach me!Originally posted by ndmmxiaomayi:LOL... you know arithmetic series, don't know geometric series? -
Ewww, we're trying to help you here and all you talk about is your ability to masturbate.. tsk tsk tsk.Originally posted by 798:i only know how to masturbate. stop mocking at me n teach me! -
Ya lor.Originally posted by ditzy:Joker right? -
ok.
/me awaiting for help. -
Google, you idiotOriginally posted by 798:i only know how to masturbate. stop mocking at me n teach me! -
cheebye lah, go wilkpedia n google search but difficult to find the exact formular.Originally posted by ndmmxiaomayi: -
Use both hands to type on the computer lah.Originally posted by 798:cheebye lah, go wilkpedia n google search but difficult to find the exact formular. -
Paper, pen, pencil, ruler, eraser invented for?Originally posted by 798:cheebye lah, go wilkpedia n google search but difficult to find the exact formular.
Go library! -
actually wat is the exact name for tis summation of numbers?
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use summation formula for AP S=(n/2)(2a+(n-1)d)Originally posted by 798:
Usually when we have a series of numbers (let's say n = 1 to 30), we use this formula to sum up the difference from 16 to 30:
= (30+29+28+...+16)
= {[n(n+1)/2] - [(n/2)(n/2+1)/2]} = {[30x31/2 - 15x16/2]} = 345
What happen if we want to find for odd number series or even number series? can someone provide me formula?
where a is the first term of the series, n is the number of terms in the series and d is the common difference
for example, find the sum of odd numbers from 1 to 30. there are 15 terms in the odd no. series. the series is an AP therefore can use the above formula coz 1,3,5,7,9....... common difference is 2
sub in the formula should get the ans 225 -
lim peh boh eng!Originally posted by ndmmxiaomayi:Paper, pen, pencil, ruler, eraser invented for?
Go library! 
u programming student dunno the formula meh? -
Originally posted by anhydrouscoppersulphate:use summation formula for AP S=(n/2)(2a+(n-1)d)
where a is the first term of the series, n is the number of terms in the series and d is the common difference
for example, find the sum of odd numbers from 1 to 30. there are 15 terms in the odd no. series. the series is an AP therefore can use the above formula coz 1,3,5,7,9....... common difference is 2
sub in the formula should get the ans 225
dont be stupid and use calculator go and sum up everything. what if you get a damn big no. and waste time -
Have you found it yet? I'm sorry I couldn't really be bothered other than to give unconstructive replies here.
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You uni student don't know the formula meh?Originally posted by 798:lim peh boh eng!
u programming student dunno the formula meh? -
But you uni triple E leh.Originally posted by 798:lim peh boh eng!
u programming student dunno the formula meh? -
thanks, i take down the steps liao, later will try out.Originally posted by anhydrouscoppersulphate:use summation formula for AP S=(n/2)(2a+(n-1)d)
where a is the first term of the series, n is the number of terms in the series and d is the common difference
for example, find the sum of odd numbers from 1 to 30. there are 15 terms in the odd no. series. the series is an AP therefore can use the above formula coz 1,3,5,7,9....... common difference is 2
sub in the formula should get the ans 225
/me muack! -
rmb this an arithmetic progression formula. geometric progression is diff.Originally posted by 798:thanks, i take down the steps liao, later will try out.
/me muack! -
but i'm not math wiz leh. most likely tis kinda knowledge will study n gave back to lecturers.Originally posted by ditzy:But you uni triple E leh. 
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agree dat calculator can do tis work by if numbers are hugh (e.g. 1 to 1000), u will type until die.Originally posted by anhydrouscoppersulphate: