Self-working card tricks explained

1. Sean Heydon - 2 red kings

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set aside two red kings face up
deal out 2 piles of 15 cards: one near them (high pile) and one near you (low pile)
they cut both those piles into two
they put one red king face down on one of the high piles
they place one of low piles on top of that king
put other red king face up on other low pile
place remaining high pile on top of that king
place that pile on top of other pile (with face down king in it)
deal out alternating piles to split them into two, watching where the face-up king is
discard pile without the king
repeat 3 times
other king will be paired with face up king

2. Ash Marlow - 4 clumps

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get 4 clumps of 4 cards out of the deck put them in 4 piles on the table
get rid of rest
they pick a pile
they pick them up, look at the 4 cards and choose one to remember
they mix them up
they put them on any of the 3 piles
they mix other two piles and then put them all on top of the other pile
deal out 4 piles of 4 face up
“did you see your card?” “yes”
they turn over pile with their card
get rid of rest of cards
count out the 4 cards onto the table, 1 2 3 4, to reverse the order
(their card is now 2nd from top)
split 4 cards into (top two in right hand) and (bottom two in left hand)
they point at one of the two pairs
get rid of left hand pair
put their card in left hand, keep top card in right
they point at one card
get rid of right card
reveal

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3. Ash Marlow - “T-R-U-T-H”: 3 piles of 3, spell out name of card

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shuffle properly
deal 3 piles of 3 cards
they choose one pile, mix it up and choose one card
they put that card on top of one of other 2 piles
put the other two cards on top of their card
put those combined piles on top of remaining pile
“lie to me and name any card that isn’t your card”
spell it out e.g.
- J-A-C-K - rest go on top
- O-F - rest go on top
- S-P-A-D-E-S - rest go on top
“you lied to me but the deck always knows the truth”
spell out T-R-U-T-H
H is their card

4. Sean Haydon - 2 piles of 7

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they shuffle
they choose any card
they place that card to the side face down
deal 2 piles of 7 cards
they place their card face down on 1 of the 2 piles
place other pile on top
place rest of cards on table (shuffle if you/they want)
they cut them and look at bottom card (e.g. 3♥️) and remember it
get rid of that pile of cards
with the small pile, they spell of the name of the card dealing down one card per letter. So e.g.:
- T-H-R-E-E-O-F-H-E-A-R-T-S
put the rest of cards on top
now …
- throw 1 card away, keep 1 card
- throw 1 card away, keep 1 card
- etc. until none left
now do it again with the kept cards …
- throw 1 card away, keep 1 card
- throw 1 card away, keep 1 card
- etc. until none left
repeat until you only have 1 card
that’s their card (e.g. 3♥️)

5. Ash Marlow - Number between 10 and 20 … add the 2 numbers together

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shuffle
look at cards openly, quickly noting the 10th card from top (tip: count in threes)
they hold deck
they choose a number between 10 and 20 e.g. 16
they deal out 16 cards
discard the rest
they add the two numbers together - so 1 + 6 = 7
they deal out 7 cards
their card is on top

6. Ash Marlow - Predict suit/value

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they shuffle
take them back
fan them out facing you and say “I’m going to make a prediction” but look at top 2 cards:
- top card (e.g. K♠️) = SUIT (so ♠️)
- 2nd card (e.g. 7♦️) = VALUE (so 7)
pull out the right card (e.g. 7♠️)
place it face down saying “That’s my prediction”
give them the pack and
they cut off any amount of cards
count out the cards on table or in your hand - “You could have chosen any amount of cards to cut off” (this step is just to reverse the order)
they deal those cut off cards into two piles
last card dealt = SUIT (e.g. K♠️ - so ♠️)
other pile’s top card = VALUE (e.g. 7♦️ - so 7)
turn over your prediction card (e.g. 7♠️)

7. Ash Marlow - Turn over bottom 3 cards

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secretly turn over bottom 3 cards
fan the deck and “pick a card”
while they look at their card, turn pack over
square up deck and they slide their card into the deck face down
“snap” - turn over top card: not theirs
“I can also show you that the second card’s not your card” - turn over top card: not theirs
place those two face-up cards back on top and then
fan deck revealing their card wrong way up

8. Gavin Wong - top and bottom card

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they shuffle
get cards back and say “I’m going to make 2 predictions” while you
fan out the cards facing you
note the bottom card (e.g. 9♥️)
look for its matching pair (e.g. 9♦️) and
pull it out and place it down face up - “That card is prediction 1”
note the top card (e.g. J♠️)
look for its matching pair (e.g. J♣️) and
pull it out and place it down face up - “That card is prediction 2”
deal cards face down until they say “Stop”
place prediction 1 (e.g. 9♥️) face up on the pile
place the rest of the deck on top and then do it again
deal cards face down until they say “Stop”
place prediction 2 (e.g. J♠️) face up on the pile
place the rest of the deck on top
now fan the cards out with most of the pack face down
your matching pair cards are immediately above the prediction cards

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You do need to prepare the deck with this one.

make a marker card with: “SUIT” left, “VALUE” right, down arrow, and on the back “12 CARDS DOWN”
prepare 4 piles: ♣️, ♥️, ♠️, ♦️ (in that order) each with whole suit in order with king at top
(watch the video!) ♣️=4, ♥️=7, ♠️=10, ♦️=stet (basically: for each suit, fan to that number and bring those cards to the top - leave ♦️ as they are)
spread out
they place marker card anywhere
separate right pile (top of spread) except card above marker
separate left pile except card below marker
put left pile on top of the right pile
turn over right card “that’s the value”
turn over left card “that’s the suit”
count out 12 cards
bingo - it matches the card’s prediction
to reset:
- place those 12 cards back on top
- then put the right (value) card on top of the left (suit) card (both face down) and then put the rest of the pack on top of them */}

With explanations of the logic

10. adultingwithanni - “When maths pretends to be magic”

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deal card face up, deal more up to 13 from the value of that card
(don’t use face cards, put them on the bottom)
repeat on new pile
keep going till you don’t have enough cards left
they choose 3 piles
put rest of cards on remainder from before
they turn over top 2 cards of 2 of the piles
add value of those cards
add 10
count out that many cards
number of cards left is value of 3rd pile’s mystery top card

Explanation

The setup

The trick relies on a fixed relationship between the number of cards in a pile and the value of the first card in that pile.

Creating the Piles: When a pile is created, you start with a card (let’s call its value ‘N’) and add cards until the count reaches 13. The number of cards in this pile will always be 14 - N.
- For example, if the first card is a 6, you will add 7 more cards to reach 13 (6, 7, 8, 9, 10, 11, 12, 13). The pile contains the initial card (the 6) plus the 7 cards you added, making a total of 8 cards.
- This follows the formula 14 - 6 = 8.
The Deck: The entire 52-card deck is divided into two main groups: the cards in the piles you created and the cards left over.

The maths behind the trick

The trick uses a simple algebraic equation to isolate the value of the third, unknown card. Let’s call the values of the top cards of the three chosen piles C1, C2, and C3.

The number of cards in these three piles are (14 - C1), (14 - C2), and (14 - C3).
All other cards form a “discard” pile. The number of cards in this discard pile (D) can be found by subtracting the cards in the three chosen piles from the total deck: D = 52 - (14 - C1) - (14 - C2) - (14 - C3)
Simplifying this equation gives us: D = 52 - 42 + C1 + C2 + C3 D = 10 + C1 + C2 + C3

This final formula is the secret. The number of cards in the discard pile is always equal to 10 plus the sum of the values of the three chosen cards (C1, C2, C3).

The reveal

When the final steps of the trick are performed, you are essentially solving for the unknown card, C3.

You reveal two cards (C1 and C2) and add their values to 10. This amount, 10 + C1 + C2, is the number of cards you count out.
The number of cards remaining in your hand is the total number of cards you started with in the discard pile (D) minus the number you counted out.
- Remaining Cards = (10 + C1 + C2 + C3) - (10 + C1 + C2)
- When you subtract, all the terms cancel out except for C3.

The number of cards left in your hand will always be the value of the third, unrevealed card. The choices made by the spectator – which piles to keep, which to reveal – have no impact on the mathematical outcome.

11. Sean Heydon - C-A-R-D-T-R-I-C-K

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spell out C-A-R-D-T-R-I-C-K face down
show them last (9th) card - that’s their card
put it on small pile
put big pile on top
deal 4 face-up piles, each time counting down from 10 to 1 but
- stop if you say the same card that is dealt (J/Q/K=10) and
- if it gets all the way down to 1, cap that pile with a face-down card
add up the values of the visible cards
their card is that many cards down

Explanation

This card trick works due to a clever mathematical principle involving fixed positioning and modular arithmetic.

How the trick operates

The trick uses the spelling of “CARD TRICK” (9 letters) to place your chosen card at a specific position in the deck. When you spell out C-A-R-D-T-R-I-C-K and remember the card on K, then reconstruct the deck, this positions your card exactly where the subsequent counting procedure will find it.

The mathematical foundation

The countdown procedure from 10 to 1 creates four piles with a predictable structure. Each pile consumes a fixed number of cards based on when a “match” occurs:

If you match at value $n$ , that pile uses exactly $11 - n$ cards (the match card plus the cards counted before it)
If you count all the way to 1 with no match, you add a face-down card, using exactly 11 cards total

This means every pile uses either $11 - n$ cards (where $n$ is the match value) or 11 cards (no match).

Why the sum reveals your card

When you add up the face values of the matched cards, the mathematics ensures this sum equals the position of your chosen card from the top of the remaining deck. This works because:

The initial spelling positions your card at a calculated distance from the top
Each pile created during the countdown removes a predictable number of cards from the deck
The relationship between cards used per pile and the match values creates an algebraic balance where the sum of match values equals the remaining distance to your card. Reddit

The trick is entirely self-working—no sleight of hand required, just mathematical inevitability built into the procedure.