what's the benifit of remembering reciprocal of first 30 numbers !!!

[catikon]

friends ...

Can smbdy plz enlighten how can we make use of remembered reciprocals during our di calculations ...

Also it would b great if smbody throw light how do u do ur calculations ..

for example ... calculation of following numbers ..

23/448 ..... 2345/87675 .... 87/897

regrds

[catikon]

Originally Posted by catikon @ Sat Oct 16, 2004 3:10 pm

friends ...

Can smbdy plz enlighten how can we make use of remembered reciprocals during our di calculations ...

Also it would b great if smbody throw light how do u do ur calculations ..

for example ... calculation of following numbers ..

23/448 ..... 2345/87675 .... 87/897

regrds

guys .. reply anyone .. or there is already a thread on this topic plz gimme the link .. i tried searching for it but cudn't find it ... (

[Jackal]

no benefit (with ref 2 ur orignal Q)

[Mayankk]

Originally Posted by catikon @ Sat Oct 16, 2004 3:10 pm

friends ...

Can smbdy plz enlighten how can we make use of remembered reciprocals during our di calculations ...

Also it would b great if smbody throw light how do u do ur calculations ..

for example ... calculation of following numbers ..

23/448 ..... 2345/87675 .... 87/897

regrds

The approach I follow in such cases is like this:
23/448 , can be intuitively said to be close to 1/20. So, we can reduce 448 by 48 and 23 by 48/20 = 2. So, 23/448 is almost = 21/400 = 0.0525. It stands me in good stead but I haven't got it frm any book , so use with common sense.
Similarly 2345/87675 is approx. 2405/90000 = 0.027
and 87/897 is well 87/900 tht is 0.097

Abt reciprocals, ahem... m not a believer in mugging up such stuff, so not the best person to help u.
And yaa, in case options are too close for comfort, take care to note whether numerator or denominator has been changed disproportionately. This can help u in determining whether the actual answer is less than or greater than this value.
Any other approches????

[Govi]

Originally Posted by catikon @ Sat Oct 16, 2004 3:10 pm

friends ...

Can smbdy plz enlighten how can we make use of remembered reciprocals during our di calculations ...

Also it would b great if smbody throw light how do u do ur calculations ..

for example ... calculation of following numbers ..

23/448 ..... 2345/87675 .... 87/897

regrds

Hey Caticon

Reciprocals Squares Square roots n Cubes n Cuberoots are the weapons with which DI can be cracked n i am sure most of the PG junta agrees with it. Its almost necessary to rote reciprocals from 1 to 30.

Now the quesiton arises how to use it. eg: 23/448 can be aproximated to 25/450 which is 1/18 and thts 5.55% since we increased the num n den the actual value will be less than this n u can search it in the options. Similarly the bigger the number is both num n den it can be reduced to two or three digits for approximation but be careful not to make a " material error" in approximation You will understand it better when u start applying it.

In general if the given fraction is a/b
a<b a+1/b+1 > a/b
a>b a+1/b+1 < a/b

Another use of kowing reciprocals is in those DI problems where pie charts are involved. The percentages can be converted to fraction form n use eg: 66.66% is 2/3 etc...

This is jus a birds eye view of the advantages of reciprocals Try the following link from PG it could help u

http://www.pagalguy.com/cat//viewtopic.php?t=1250

n try n find some books on Vedic Maths the shortcuts mentioned are of immense use

Hope this small contribution answers a part of ur problem

GOVI..................

[pabby]

The best things for such questions will be approximations. If the answer choices are closer then go for some better approximation. If the choices are far just do some random approximations i.e take 978 as 1000 etc.