Combinations and Permutations
Combinations and Permutations
Permutation and combination related questions are common in PSC and Bank exams.
Before going to Combinations and Permutations, first lean about factorial.
If n is a positive integer then, factorial of n is denoted as n!.
5! = ( 1 x 2 x 3 x 4 x 5 ) = 120
4! = (1 x 2 x 3 x 4 ) = 24
Permutations are for lists of items, whose order matters and combinations are for group of items where order doesn’t matter. in other words,
- When the order of items doesn\\\'t matter, it is called as Combination.
- When the order of items does matter it is called as Permutation.
The number of permutations of n objects taken r at a time is determined by using this formula:
P(n,r)=n!/(n−r)!
Permutation: Listing your 3 favourite football team in order, from list of 10 teams. P(10,3) = 720.
The number of combinations of n objects taken r at a time is determined by using this formula:
C(n,r)=n!/((n−r)!r!)
Combination: Picking a team of 3 people from a football coaching group of 10. C(10,3) = 10!(3!(10−3)!) = 120.
1) ഇന്ത്യയിലെത്തിയ വിദേശികൾ അവർ വന്ന ക്രമത്തിൽ = PDEF .
Portagese, Dutch,English, French.
2) വൈറ്റമിനുകൾ.
കൊഴുപ്പിൽ ലയിക്കുന്നവ= ADEK.
ജലത്തിൽ ലയിക്കുന്നവ = BC.
3) കൂടുതൽ States അധികാരപരിധിയിലുള്ള ഹൈകോടതി = ഗുഹാവതി. ഏതൊക്കെ?.
States Code = MAAN ( മിസോറം,അരുണാചൽപ്രദേശ്, അസം,നാഗാലാൻഡ് ).
4) യുദ്ധങ്ങൾ അവസാനിപ്പിച്ച സന്ധികൾ.
കർണാട്ടിക് യുദ്ധങ്ങൾ...
What is the divisibility by 2 Rule?.
Even numbers are multiples of 2. A number is even if ends in 0,2,4,6, or 8.
What is the divisibility by 3 rule?.
A number is divisible by 3 if the sum of its digits is divisible by 3.
372, for instance, is divisible by 3 since sum of its digits (3+7+2) is 12. And 12 is divisible by 3.
What is the divisibility by 4 rule?.
A number is divisible by 4 if the number\'s last two digits are divisible by 4.
9,312, for instance, is divisible by 4 since its last 2 digits are 12. And 12 is divisible by 4.
What is the divisibility by 5 rule?.
A number is divisible by 5 if its last digit is a 0 or 5.
What is the divisibility by 6 rule?.
Since 6 is a multiple of 2 and 3, the rules for divisibility by 6 are a combination of the rule for 2 and the rule for 3.
Divisibility by 8 Rule.
A number passes the test for 8 if the las...
The quickest way to calculate percentages is to multiply numbers first and handle two decimal places later.
For example, 20% of 70 is 20 x 70 = 1400, so the answer is 14. .
70% of 20 is also 14.
To calculate the percentage of 72 or 29, then round up and down to the nearest multiple (70 and 30 respectively) to get a quick approx result.
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