Performer show four cards and out of which one is a blank face card which is shown and kept face down. The remaining three cards are shown to have two spots on each card . The top card , bottom card and the middle one all have two spots . One by one the performer magically transfers three dots onto the blank card . Now he shows once again all the three cards to have one spot on each of them .. Once again he magically transfers the last three dots one from each card onto the Blank face card .. and finally all the three cards are shown to be completely blank now !!The blank cards are kept in an envelope and the earlier blank face card shown has now all the six dots on it !! All the cards can be later given out for inspection .
SEE DEMO THE LINK………..
https://www.youtube.com/watch?v=RZGiNq6Nymo&t=5s