Question

In how many ways can the letters of the word 'UNIVERSAL' be arranged so that E, R, S always occur together?

Answer 1

$\underset{–}{U}\underset{–}{N}\underset{–}{I}\underset{–}{V}\left(E\underset{–}{R}S\right)\underset{–}{A}\underset{–}{L}$

As (ERS) occur together

$\therefore$ no of letters are

$6+1\left(ERS\right)=7$

$\therefore$ no' of ways to arrange

is 7! bust ERS

can also change their

Position $\therefore$ no. of

ways are $7!\times 3!=30240$