Use of letters to denote numbers

A letter look consists of three rings marked with 15 different letters. If N denotes the number of ways in which it is possibel to make unsuccessful attempts to open lock, then

A letter look consists of three rings marked with 15 different letters. If N denotes the number of ways in which it is possibel to make unsuccessful attempts to open lock, then

Write the following using a letter Four times a number is 24

Whatdoos the letter 'P' denote in the term 'PAN' as used in financial transactions ?

A letter lock consists of three rings marked with 15 different letters . If N denotes the number of ways in which it is possible to make unsuccessful attempts to open the lock, then

The maximum number of letters that can be used as a symbol of an element is ……….

If three letters are placed in three addressed envelopes then the mean and variance of X where X denotes the number of correct despatches.