Last seen on Big Brother Variety on Sun. Nice effect....

Magician brings out an envelope with his prediction inside.
He randomly chose 4 members of the audience.
The 1st one randomly picks any 4 digits frm 1 to 10
The 2nd picks 5 digits, the 3rd 6 digits n the 4th 7digits.

He brings out a calculator n handed it to another spectator
who then total up the 4 sets of chosen nos.

The total tallys with his prediction.

He mentioned that many magicians knows this effect unfortunately i'm
one of them...anyone knows the name of this effect n by whom? Cheers.