There were 5 pupils in a room. Each pupil shook hands once with each of the other pupils. How many handshakes took place ?
(a) 5
(b) 10
(c) 15
(d) 20
a
There were 5 pupils in a room. Each pupil shook hands once with each of the other pupils. How many handshakes took place ?
(a) 5
(b) 10
(c) 15
(d) 20