Permutations & Combinations Questions (855)

How many different squares are there on a chessboard?
254. The number of words which can be formed using all the letters of the word "NARENDRABHAI" such that no two non-repeated letters occur together is:
How many numbers of 4 digits can be made with the digits 0, 1, 2, 3, 4, 5 which are divisible by 3, digits being unrepeated in the same number? How many of these will be divisible by 6?
Let $A = \{1, a_1, a_2, \ldots, a_{18}, 77\}$ be a set of integers with $1 < a_1 < a_2 < \ldots < a_{18} < 77$. Let $A+A = \{x+y : y\in A\}$ contain exactly 39 elements. Then $a_1+a_2+\ldots+a_{18}$ equals
The number of integral solution(s) of the equation xyz = 360 is 180 m, then m equals:
The number of solutions $(n_1, n_2)$ which satisfy $n_1 n_2 = 2n_1 - n_2$, where $n_1, n_2 \in \mathbb{I}$ (integers) is
A positive integer n is called strictly ascending if its digits are in ascending order, e.g. 2368 and 126 are ascending numbers but 21789 is not. The number of strictly ascending numbers < 109 is
The number of three-digit numbers $\overline{abc}$ which satisfy $a \leq b > c$ is
Find the number of integers between 1 and 100000 having sum of the digits 18.
Nine people sit around a round table. The number of ways of selecting four of them such that they are not from adjacent seats, is?
If the number of$seven-digit$numbers, such that the sum of their digits is even, is m$\cdot n$$\cdot 10$; n m, n$\i_n {1, 2, 3,$$\ldots, 9}, then$m + n$is equal to _______$
The number of ways, in which the letters A, B, C, D, E can be placed in the 8 boxes of the figure below so that no row remains empty and at most one letter can be placed in a box, is:
For n$\ge 2, let S denote the set of all subsets of {1, 2$$\ldots..., n} with no two consecutive numbers. For example n {1, 3, 5}$$\i_n$$S_{6}$$, but {1, 2, 4}$$\notin$ S. Then n ( S ) is equal to ________ 6 5
Let m and n, ($m < n)$be two$2-digit$numbers. Then the total numbers of pairs$(m, n)$, such that gcd$(m, n)$= 6, is ________
Let $N$ be the number of four digit even numbers such that if 3 is one of the digits, then 5 is the succeeding digit. If $N = P_1^\alpha P_2^\beta P_3^\gamma$ ($P_1,P_2,P_3$ are primes, $\alpha,\beta,\gamma\in\mathbb{N}$), then $P_1+P_2+P_3$ is
Let $N$ be the number of four digit even numbers such that if 3 is one of the digits, then 5 is the succeeding digit. If $N = P_1^\alpha P_2^\beta P_3^\gamma$ ($P_1,P_2,P_3$ are primes, $\alpha,\beta,\gamma\in\mathbb{N}$), then $P_1+P_2+P_3$ is
A committee of 11 members is to be formed from 8 males and 5 females. If m is the number of ways the committee is formed with at least 6 males and n is the number of ways the committee is formed with at least 3 females, then:
The number of ways in which n distinct objects are placed in two distinguishable boxes so that no box remains empty, is
If the first letter is R and the last letter is E in the word MEDICINE, then the total number of all such words is:
If \(P(n) = 2n
If \(\lambda\) be the number of 3-digit numbers of the form \(xyz\) with \(x
The last digit of \((1! + 2! + \ldots + 2005!)^{500}\) is
How many 7-digit numbers of the form 7777777 (using digits 5 and 7 only) are divisible by 35?
In how many ways can the letters of the word CINEMA be arranged so that the order of vowels does not change?
Other than the letter S, the seven letters M, I, I, I, P, P and I can be arranged in \(\dfrac{7!}{2! \cdot 4!} = 7 \cdot 5 \cdot 3\). Now four S can be placed in eight spaces in \({}^8C_4\) ways. Therefore, the required number of ways is \(7 \cdot 5 \cdot 3 \cdot {}^8C_4 = 7 \cdot {}^6C_4 \cdot {}^8C_4\). The required number of ways is:
In how many different ways can three persons A, B, C having respectively 6, 7 and 8 one-rupee coins donate 10 rupees collectively?
The number of ways of arrangement of 5 letters of the word "IITJEE" is
To form a committee of 11 persons from 8 males and 5 females, find the number of ways \(m\) to form a committee with at least 6 males. Also find the number of ways \(n\) to form a committee with at least 3 females. What is the value of \(m\) and \(n\)?
Consider three boxes, each containing 10 balls labelled 1, 2, ..., 10. Suppose one ball is randomly drawn from each of the boxes. Denote by \(n_i\) the label of the ball drawn from the \(i^{\text{th}}\) box, \((i = 1, 2, 3)\). Then, the number of ways in which the balls can be chosen such that \(n_1
In IIT-JEE 2016, a multiple choice question has four alternatives in which two or more than two are correct. Number of ways in which this question can be answered, is :
If n+2C8 : n-2P4 = \(\frac{57}{16}\), then n is equal to
The number of ways in which 2n objects of one type, 2n of another type and 2n of a third type can be divided between 2 persons so that each may have 3n objects is \(an^2 + bn + \gamma\). Find the value of \((a + b + \gamma)\).
The number of ways in which 5 boys and 3 girls can be seated on a round table if a particular boy B1 and a particular girl G1 never sit adjacent to each other, is:
A scientific committee is to be formed from 6 Indians and 8 foreigners, which includes at least 2 Indians and double the number of foreigners as Indians. Then the number of ways, the committee can be formed, is:
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:
There are 10 girls and 8 boys in a class room including Mr. Ravi, Ms. Rani and Ms. Radha. A list of speakers consisting of 8 girls and 6 boys has to be prepared. Mr. Ravi refuses to speak if Ms. Rani is a speaker. Ms. Rani refuses to speak if Ms. Radha is a speaker. The number of ways the list can be prepared is a 3 digit number \(n_1 n_2 n_3\), then \(|n_3 + n_2 - n_1| = \)?
Number of ways in which 12 different things can be distributed in 5 sets of 2, 2, 2, 3, 3 things is
How many 7 digit numbers can be formed by using only the digits 5 and 7 such that number formed is divisible by both 5 and 7?
How many five-digit numbers can be made having exactly two identical digits?
There are n different books and each book has p copies. The number of selection of books from these is
How many 4-digit numbers \(N = \overline{abcd}\) are there such that \(4000 \leq N
275. \(ABCD\) is a rectangle with vertices \(A(0,0)\), \(B(m,0)\), \(C(m,n)\) and \(D(0,n)\) with \(m, n \in N\). Points are chosen starting from \(A_0(0,0) \to A_1(x_1,y_1) \to A_2(x_2,y_2)\) and so on. Such that for \(A_k(x_k,y_k) \to A_{k+1}(x_{k+1},y_{k+1})\), exactly one of the following result holds:(i) \(x_{k+1} = x_k + a\) and \(y_{k+1} = y_k\)(ii) \(x_{k+1} = x_k\) and \(y_{k+1} = y_k + b\)for some \(a, b, k \in N\)If \(m = n = 6\), number of paths from \(A_0\) to \((m,n)\) consisting of exactly two perpendicular path with \(a, b \in \{1,2\}\).
6 balls marked as 1, 2, 3, 4, 5 and 6 are kept in a box. Two players A and B start to take out 1 ball at a time from the box one after another without replacing the ball till the game is over. The number marked on the ball is added each time to the previous sum to get the sum of numbers marked on the balls taken out. If this sum is even, then 1 point is given to the player. The first player to get 2 points is declared winner. At the start of the game, the sum is 0. If A starts to take out the ball, find the number of ways in which the game can be won.
How many words can be formed using all the letters of the word ALLAHABAD?
In how many steps can a 12-step staircase be climbed taking one step or 2 steps at a time?
In how many ways can the letters of the word PERMUTATIONS be arranged if there are always 4 letters between P and S?
Find the number of ways in which two small squares can be selected on the normal chessboard if they are not in same row or same column.
How many different words can be made from the word ORDINATE so that the vowels occupy the odd places?
A batsman scores exactly a century by hitting fours and sixes in twenty consecutive balls. In how many different ways can he do it if some balls may not yield runs and the order of boundaries and overboundaries are taken into account?
If \(A = \{1, 2, 3, 4\}\), \(B = \{1, 2, 3, 4, 5, 6\}\) and \(f: A \to B\) is an injective mapping satisfying \(f(i) \neq i\) for all \(i \in A\), then number of such mappings are: