Parallelogram 39 Level 1 29 May 2025Multifactorials

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Noun: Parallelogram Pronunciation: /ˌparəˈlɛləɡram/

  1. a portmanteau word combining parallel and telegram. A message sent each week by the Parallel Project to bright young mathematicians.
  • Tackle each Parallelogram in one go. Don’t get distracted.
  • Finish by midnight on Sunday if your whole class is doing parallelograms.
  • Your score & answer sheet will appear immediately after you hit SUBMIT.
  • Don’t worry if you score less than 50%, because it means you will learn something new when you check the solutions.

1. Multifactorials

You may have heard of factorials, but we bet you’ve never heard of a multifactorial!!

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1 mark

1.1 How would you calculate 6!

  • 6 × 5 × 4 × 3 × 2 × 1
  • 6 + 5 + 4 + 3 + 2 + 1
  • 6 × 3 × 1
  • 6 × 6 × 6 × 6 × 6 × 6
  • (Not answered)
1 mark

1.2 How would you find 6!! ?

  • 6! × 6!
  • 6 × 5 × 3 × 1
  • 6 × 4 × 2
  • 6 × 5 × 4
  • (Not answered)
2 marks

1.3 Given that 6! = 720, what is 7! ?

Correct Solution: 5040

Show Hint (–1 mark)
1 mark

7! = 7 × 6!

2. A coin challenge

2 marks

2.1 Max has a 1p coin, a 2p coin and a 5p coin.

Which sum of money can he not make?

  • 4p
  • 5p
  • 6p
  • 7p
  • 8p
  • (Not answered)

3. Dozen it make sense?

2 marks

3.1 What is twelve thousand plus twelve hundred plus twelve?

  • 12,121
  • 13,212
  • 121,212
  • 132,012
  • 1,212,012
  • (Not answered)

Before you hit the SUBMIT button, here are some quick reminders:

  • You will receive your score immediately, and collect your reward points.
  • You might earn a new badge... if not, then maybe next week.
  • Make sure you go through the solution sheet – it is massively important.
  • A score of less than 50% is ok – it means you can learn lots from your mistakes.
  • The next Parallelogram is next week, at 3pm on Thursday.
  • Finally, if you missed any earlier Parallelograms, make sure you go back and complete them. You can still earn reward points and badges by completing missed Parallelograms.

Cheerio, Simon.