Here are some tricks you can baffle your Muggle friends with and not have the Ministry after you. Can you tell me why they work?
Write 4 or 5 character number, add the digits and write answer (A), cross out one of original digits, subtract A from remaining number. Magician adds digits until a one digit number remains, subtracts from 9 to get missing number. If single digit is 9, answer is 9 or 0.
Spectator thinks of a card, add the number (Jack 11, Queen 12, King 13) to the next highest number (i.e. the thought-of number plus one), multiply result by 5, add number for suit (Club 1, Diamond 2, Spade 3, Heart 4), tell you number. Deduct 5, right digit is suit, others give the number.
Circle four adjacent dates on a calendar (two in one week, two immediately below), given total. Divide by 4, subtract 4, result is top left date (others +1, +7, +8).
Circle 9 adjacent dates on a calendar (3 on one week plus 2 weeks below), given total of 2 diagonal corners. Divide by 2 gives mid figure (others -8, -7, -6, -1, +1, +6, +7, +8).
Use a stack of 8 business cards, blank one side, either side up, but secretly reverse the orientation (side) of the bottom card, then hand the pack to a spectator (perhaps hand them under the table, reversing the bottom card). Have spectator reverse top two cards and cut them placing bottom set on top. Repeat as many times as liked, while you talk about having analyzed the person as a 5-3 personality. have spectator spread the cards out and five will be face up or down, and 3 the other way (or perhaps 7-1, and if so have them try reversing cards again).
Hand spectator a full matchbox and, without watching, have him take out three equal sets of matches while you look away, referred to as A, B, C. Have spectator remove 3 from A & C, add them to B, remove remaining A matches. Count matches in C and remove equivalent number from B, then discard C. (There are now 9 matches in B). Ask spectator to hand you as many, or as few matches as he likes. Bring those matches to your head, concentrate, and predict how many matches left on the table (9 – one in your hand). Remaining total is always 3x number initially moved from both A & C to B.
Tear four squares of paper, write numbers on each side of each piece, 1/2, 3/4, 5/6, 7/8. Trick 1: write a prediction on a card [18], hand it to a spectator to keep until the end; give squares to another spectator and tell to lay out with odd number figures showing, then tell him to turn two over so you have 2 odd and 2 even – answer will be 18.
Players A and B select a number between 1 and 10 in turn, adding to previous sum. First to 100 wins. Get your totals to come to 12, 23, 34, 45, 56, 67, 78, 89.