MEDIUM
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IMPORTANT
Earn 100

A four digit number consists of two distinct pairs of repeated digits (for example 2211, 2626 and 7007). Find the total number of such possible numbers that are divisible by 7 or 101 but not both.

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Important Questions on Counting

MEDIUM
IOQM - PRMO and RMO
IMPORTANT
m and n are two positive integers satisfying 1mn40. Find the number of pairs of m,n such that their product mn is divisible by 33.
EASY
IOQM - PRMO and RMO
IMPORTANT
How many 7 digit palindromes (numbers that read the same backward as forward) can be formed using the digits 2, 2, 3, 3, 5, 5, 5?
HARD
IOQM - PRMO and RMO
IMPORTANT
Ajay refuses to sit next to either Bharat or Chandan. Deepak refuses to sit next to Enees. How many ways are there for the five of them to sit in a row of 5 chairs under these conditions?
HARD
IOQM - PRMO and RMO
IMPORTANT
If there are N integers between 100 and 999, inclusive, have the property that some permutation of its digits is a multiple of 11 between 100 and 999? For example, both 121 and 231 have this property. Then find the value of N-15.
HARD
IOQM - PRMO and RMO
IMPORTANT
The numbers 1, 2, 3, 4, 5 are to be arranged in a circle. An arrangement is bad if it is not true that for every n from 1 to 15 one can find a subset of the numbers that appear consecutively on the circle that sum to n. Arrangements that differ only by a rotation or a reflection are considered the same. How many different bad arrangements are there?
MEDIUM
IOQM - PRMO and RMO
IMPORTANT
A student must choose a program of four courses from a menu of courses consisting of English, Algebra, Geometry, History, Art, and Latin. This program must contain English and at least one mathematics course. In how many ways can this program be chosen?
EASY
IOQM - PRMO and RMO
IMPORTANT
What is the sum of the last two digits of the integer 1!+2!+3!++2005!?
MEDIUM
IOQM - PRMO and RMO
IMPORTANT
There are N three digit numbers, lying between 100 and 999 inclusive, have two and only two consecutive digits identical. Then find the value of N9.