Find the number of ways of arranging the letters of the word SINGING so that
the two G's come together

Explanation

The word SINGING has 2 I's, 2 G's and 2 N's and one S. Total 7 letters.

Treat two G's as one unit. Then we have 5 letters 2 I's, 2 N's and one S + one unit of 2 G's=6 can be arranged in `(6!)/(2! 2!)=(720)/(2xx2)`
=180 ways.
Now the two G's among themselves can be arranged in one way. Hence the number of received permutations `=180xx1=180`.