Intergalactic Adventure - Challenge 6

Ready for a mathematical space adventure? Complete your Intergalactic Passport Application Form and prepare for a journey to the Planet Turasmara.

Created by Scottish Mathematical Council

Ic434

Challenge 6: Last Card Diner

You've made it to Planet Turasmara, and you're really hungry from your space journey so you stop off at the Our World Diner. One of the pastimes at the Our World Diner is a game called LAST CARD. If you’re going to dine here you need to learn to play!

You will need 16 cards (numbered 1-16).

>> download number cards

Let’s start with JUST the first 4 card for now. Take the cards numbered 1 to 4 only and arrange them in order with the 1 face up on top... then 2 ... then 3 ... finally 4.

Now:

  • Move the top card to the bottom of the pack.
  • Discard the next card.
  • Move the new top card to the bottom of the pack.
  • Discard the next card.
  • Continue like this until you are left with only one card.

What is the number on that card? This is the LAST CARD.

Now try the same with 5 cards (1-5 in order). What do you notice?

Try some different numbers. Can you predict the number of your LAST CARD?

Extra challenge!

What number would be on the LAST CARD if there were 16 cards?.

If you found that easy, try this: if there were 100 cards, what would be the LAST CARD?!

Mission complete!

Congratulations, you have made it to the end of your intergalactic space mission! Did you manage to solve all six challenges? You can check your answers on the next page.

(If you are arriving at the Intergalactic Adventure on this page, you can go back to the Introduction and Challenge 1 to start you off)

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