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sandeep800
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sandeep800
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I think this method is also pretty neat !
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This is a great shortcut,

so for

Inc inc (p1+p2)
pos*po =+ so + is sign outside second brackets

Inc decr (p1-p2)
pos*neg = - so - is sign outside second brackets

decr decr (-p1--p2) which is same as -p1+p2
neg*neg = + so + is sign outside second brackets

decr inc (-p1+p2)
neg*pos = - so - is sign outside second brackets

is this correct?
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Yes, it is certainly a good approach in some cases. I have discussed the derivation and application of this formula on the blog (link given in my signature).
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sandeep800


Thanks much sandeep800,

This shortcut formula will actually save lot of time. One question regarding this, what happens when the initial change is a decrease? I mean as per the given formula p1 is a decrease? Can you show one more example on that please? :-)








HI Guys.
I found a good method while going thru a book in case u guys dont know!!!

suppose a questions says first the price of an article increase by 20% then after that price got reduced by 5%
normally we calculate seprately for some original price
like say
(1.2)x and then to calculate 5 % reduce we calculate 5% of (1.2)x

shortcut is we can calculate by formula (p1+/-p2)+/-((p1*p2)/100)
p1-->1st percentage
p2 -->2nd one
sign of + or - in first bracket depending on increase or decrease
in second bracket sign outside it will be product of initial sign of p1 and p2 like for both decrease +ve*-ve=-ve
i know u may find it difficult to cram but see an example u dont need to learn at all

sol for above eg

20-5-((20*5)/100)
15-1
14% of original value

another example
suppose length increase by 20% breadth by 30 % then overal area increase wil be 20+30+(20*30)/100)=56% more of original
..
we use -ve sign for reduction ,+ve for increase and if both are decrease then in product of p1*p2 part value will be +ve (since -ve*-ve=+ve)


Hope it help u guys..!!
thanx
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