How many 3 digit numbers can be formed from the digits 2 , 3 , 5 , 6 , 7 and 9 which are divisible by 5 and none of the digit is   repeated ?

Find the number of 4 letter words, with or without meaning, which can be formed out of the letters of the word ROSE, where the repetition of the letters is not allowed.                 

Given 4 flags of different colours, how many different signals can be

generated, if a signal requires the use of 2 flags one below the other?                 

How many 2 digit even numbers can be formed from the digits

1, 2, 3, 4, 5 if the digits can be repeated?                  

Find the number of different signals that can be generated by arranging at

least 2 flags in order (one below the other) on a vertical staff, if five different flags are  available.                      

Find the number of permutations of the letters of the word ALLAHABAD.            

How many 4-digit numbers can be formed by using the digits 1 to 9 if

repetition of digits is not allowed?

How many numbers lying between 100 and 1000 can be formed with the

digits 0, 1, 2, 3, 4, 5, if the repetition of the digits is not allowed?                 

Find the value of n    ⁿP₅   =  42 ⁿP₃ ,        n > 4  

Find the value of n        3 ⁿP₃   =  5   ^{n – 1}P₃ ,        n > 4