Note - I am not sure of the answer this is the first time I have solved the problem. If anyone knows the solution, tell me if I am right or wrong
the first person will shake hands with 48 people
the second person will shake hands with 47 people excluding the first
and so on
until last 2 remain
so it forms an A.P
a = 48
d = -1
2 = 48 -n+1
n = 47
s = n/2*(2a+(n-1)*d)
s = 47/2 * (2*48 +(47-1)*-1)
s = 47/2 *(96 -46)
s = 47/2*(50)
s = 47*25
s = 1175