Number plugging strategy?

Question

Could anyone help me with a good number plugging strategy,

that is very easy to implement i.e doesn't need me to think much and waste time??

I realised that I lack the right approach to plugging numbers.

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retro · Answer

Well; you are asking a very generic question. I am basically pointing at that I use number plugging strategies for DS questions in a different way than I do for problem solving. Even within problem solving, I plug numbers very frequently to solve rate problems, percentages and ratios.

But I'd say this:

1. In any problem if you had to plug the numbers and evaluate the answer choices, you could start working with 0, 1, -1, 2 and -2. I read this tip in some book 9do not remember which one) and if your answer is not deducible from just these, go ahead to involve -1/2 and 1/2 as well. This strategy is useful in DS questions especially.

2. For percent questions, your choice depends on what exact numbers are used in the question. For example in a question that relates to finding successive percentages (rebate of 20% first and then 25%), I start with 100. In other cases where we have multiple percentages (20% of people researched had one habit and 30% had another) kind of questions, I start with 1.

3. In rate and work questions, I use the Least Comm Multiple. If 3 men work on some task 20 hours and 4 people do the same work in 10 hours, I will try to find the LCM of 60 and 40 and then assign the unit rate of work as 2 units per woman per hour and 3 units per man per hour.

I am not sure if you are asking for anything more. But in case you need more detail, shoot back.

Regards
Rahul

akhileshgupta05 · Answer

Sorry I forgot to mention I needed a strategy for DS questions only. I am aware of the rest, I use precisely the same.

You DS strategy seems interesting, I guess it would work.

Thanks.

retro · Answer

Thanks for the Kudos

Regards
Rahul

KarishmaB · Answer

First of all, plugging in numbers for DS questions should be a back up plan, say, if nothing else seems to be working. It is a huge waste of time and you keep wondering if you have missed considering a case. That said, a few questions need to be done by plugging in numbers.
For those, remember that number properties vary for numbers lying in the following regions:
x < -1
-1< x < 0
0 < x < 1
x > 1

Properties like x < x^2, x < x^3, x < 1/x etc hold in some regions and not in others.
The numbers at the boundary (e.g. x = -1/0/1) will seldom help since that's where relations become equal. 
Say I want to know where x^2 < x?
At x = 1 and x = 0, both terms are equal. So instead check for x = 1/2, -1/2, 2, -2
That said, do not forget to check for the boundary conditions. Sometimes, they are the key to the correct answer e.g. x < 0 or x <= 0.

puneetj · Answer

x < -1
-1< x < 0
0 < x < 1
x > 1

by Karishma is very useful.....

100 for percent problems
whole numbers for LCM, HCF problems

akhileshgupta05 · Answer

Makes sense. Thank you

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Number plugging strategy?

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