Using maths, perform a card trick to fool friends and family.
What you need:
- a deck of cards
- someone to fool
What to do:
1. Deal out cards into three columns as shown in the video below, adding one card to the first column, then the second and then the third, and so on. You need to have the deck upside down so that you flip the cards over each time. Deal out eight rows (24 cards in total). Put any other cards away.
2. Ask someone to select a card, but not to tell you what it is. Tell them to remember their card. Ask if their card is in column 1, 2 or 3.
3. Push down the column the select, carefully making sure all cards stay in order. Do this for the other two columns as well. Now for the first tricky part, stack the piles of cards on top of each other, making sure the pile with the person’s card is on the bottom.
4. Flip the cards over and deal out the cards into three columns again, flipping the cards over each time. NOTE: The selected card will be in the first three rows.
5. Ask the person, which column is their card in now. Push down the selected column first, again making sure the cards stay in order. Do this for the other two columns and again stack the piles so that the selected card’s group is at the bottom.
6. Flip the cards over and deal the cards into the columns for a third time. NOTE: The selected card will now be in the first row.
7. Ask the person again, which column is their card in. Push down the selected column. Push down the other two columns and discards them to the side. Take the selected column and flip it over so the cards are upside down.
8. Deal out the cards, one at a time, into four piles, cards face down. NOTE: The selected card will be the first one dealt out.
9. Ask the person to choose two piles. If they choose the one that their card is in (eg. top left pile), remove the other two. If they choose piles that don’t contain their card, remove the ones they selected.
10. Gather the cards, making sure you put the pile with the selected card on the bottom. Deal the cards out into four piles, one card per pile. NOTE: The selected card will be the last card dealt out.
11. Ask the person to choose two cards. If they choose the one that their card is in (eg. bottom right), remove the other two. If they choose cards that aren’t their card, remove the ones they selected.
12. Push the two remaining cards together. Ask the person to choose a card. If they choose the other card (eg. not their selected card), remove it, and flip over their card. If they choose their selected card, simply flip it over.
How it works:
This is all about the maths. You deal eight rows of cards so that you only have to do the columns three times (you actually could deal nine rows but this makes the last section slightly more difficult). When you get their column, it contains eight cards. Putting this column on the bottom so when you flip the deck over they’ll be on the top ensures that these eight are dealt first, meaning their card will be somewhere in the first three rows when you deal them out again. When you put this column on the bottom of the deal and flip it over so they are on the top, the selected card will be one of the first three cards dealt out. When they select their column for the third time, you’ll know their card is the card at the top of that column. Then you just need to keep track of the card when you deal the cards out face down. You know exactly where the card is so you make sure when the person chooses piles, you DON’T remove the pile their card is in. Keeping working until only their card is left.
Back to Home Science activities.