EASY
JEE Main/Advance
IMPORTANT
Earn 100
Find the total number of ways of selecting two numbers from the set of first natural numbers such that difference of their square is divisible by .

Important Questions on Permutation and Combination
MEDIUM
JEE Main/Advance
IMPORTANT
A four digit number plate of a car is said to be lucky if sum of first two digit is equal to sum of last two digit. Then find the total number of such lucky plate. (Assume all are four digit number)
HARD
JEE Main/Advance
IMPORTANT
Let each side of the smallest square of a chessboard is one unit in length.
Find the total number of squares of side length equal to and whose side is parallel to the side of the chessboard.
Find the sum of the area of all possible squares whose side is parallel to the side of chessboard.
Find the total number of rectangles (including squares) whose side parallel to side of chess board.
EASY
JEE Main/Advance
IMPORTANT
A person is to walk from to . However, he is restricted to walk only to the right of or upwards of , but not necessarily in the order shown in the figure. Then find the number of paths from to .

EASY
JEE Main/Advance
IMPORTANT
The number of signals that can be made with flags each of different colour by hoisting or or above the other, is
EASY
JEE Main/Advance
IMPORTANT
chairs are numbered from to . Two women and three men wish to occupy one chair each. First, the women choose the chairs from amongst the chairs marked to then the men select the chairs from among the remaining. The number of possible arrangements is
MEDIUM
JEE Main/Advance
IMPORTANT
Number of words that can be made with the letters of the word if each word neither begins with nor ends in is
MEDIUM
JEE Main/Advance
IMPORTANT
The number of words that can be formed by using the letters of the word that start as well as end with is
MEDIUM
JEE Main/Advance
IMPORTANT
boys & girls are sitting in a row of seats. Number of ways in which they can be seated so that not all the girls sit side by side, is
