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The interior angles of a regular polygon measure 160° each. The number of diagonals of the polygon are

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Important Questions on Permutation and Combination

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Mathematics>Algebra>Permutation and Combination>Combination
The number of 4 digit numbers without repetition that can be formed using the digits 1, 2, 3, 4, 5, 6, 7 in which each number has two odd digits and two even digits is
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Mathematics>Algebra>Permutation and Combination>Combination
The number of 4 letter words (with or without meaning) that can be formed from the eleven letters of the word EXAMINATION is
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Mathematics>Algebra>Permutation and Combination>Combination
The number of 6 digit number that can be formed using the digits 0, 1, 2, 5, 7 and 9 which are divisible by 11 and no digit is repeated is:
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Mathematics>Algebra>Permutation and Combination>Combination
The value of (2⋅1P0−3⋅2P1+4⋅3P2−........ up to 51th term)+( 1!−2!+3!−....... up to 51th term) is equal to 
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Mathematics>Algebra>Permutation and Combination>Combination
How many ways are there to arrange the letters of the word EDUCATION so that all the following three conditions hold?
- the vowels occur in the same order EUAIO,
- the consonants occur in the same order DCTN,
- no two consonants are next to each other.
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Mathematics>Algebra>Permutation and Combination>Combination
Two families with three members each and one family with four members are to be seated in a row. In how many ways can they be seated so that the same family members are not separated ?
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Mathematics>Algebra>Permutation and Combination>Combination
The number of four-digit numbers strictly greater than 4321 that can be formed using the digit 0,1,2,3,4,5 (repetition of digits is allowed) is:
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Mathematics>Algebra>Permutation and Combination>Combination
If all the seven letters of the word LEADING are permuted in all possible ways and the words thus formed are arranged as in the dictionary order, then the word in 2017th place is
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Mathematics>Algebra>Permutation and Combination>Combination
The sum of the digits in the unit's place of all the 4 - digit numbers formed by using the numbers 3, 4, 5 and 6, without repetition is :
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Mathematics>Algebra>Permutation and Combination>Combination
From 6 different novels and 3 different dictionaries, 4 novels and 1 dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. The number of such arrangements is:
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Mathematics>Algebra>Permutation and Combination>Combination
Six identical coins are arranged in a row. The number of ways in which the number of tails is equal to the number of heads is
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Mathematics>Algebra>Permutation and Combination>Combination
The total number of permutations of n(>1) different things taken not more than r at a time, when each thing may be repeated any number of times is
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Mathematics>Algebra>Permutation and Combination>Combination

If the number of all possible permutations of the letters of the word MATHEMATICS in which the repeated letters are not together is 90X, then X=

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Mathematics>Algebra>Permutation and Combination>Combination
The number of words (with or without meaning) that can be formed from all the letters of the word"LETTER" in which vowels never come together is.....
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Mathematics>Algebra>Permutation and Combination>Combination
There are 10 red and 5 yellow roses of different sizes. If x is the number of garlands that can be formed with all these flowers so that no two yellow roses come together and y is the number of garlands formed with all these flowers so that all the red roses coming together, then 2x-y10!=
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The number of four-letter words that can be formed with letters a, b, c such that all three letters occur is
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Mathematics>Algebra>Permutation and Combination>Combination
In a 12 storied building, 3 persons enter a lift cabin. It is known that they will leave the lift at different floors. In how many ways can they do so if the lift does not stop at the second floor?
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Mathematics>Algebra>Permutation and Combination>Combination
All possible numbers are formed using the digits 1, 1, 2, 2, 2, 2, 3, 4, 4  taken all at a time. The number of such numbers in which the odd digits occupy even places is
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Mathematics>Algebra>Permutation and Combination>Combination
The number of all 3-digits numbers abc (in base 10) for which 10 is
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Mathematics>Algebra>Permutation and Combination>Combination
Two girls and four boys are to be seated in a row in such a way that the girls do not sit together. In how many different ways can it be done?