What Comes Next? #424

Pattern puzzle 424 card

Challenge type: What Comes Next?  ·  Difficulty: ★★★★★ Super tricky

Computers are brilliant at spotting patterns, and so are you. Look carefully at this row.

Pattern: 21, 22, 24, 27, 31, 36, then a question mark. Choices: A: 40; B: 42; C: 44; D: 72.
What comes next: A, B, C or D?

The pattern in words: 21, 22, 24, 27, 31, 36, and then… what?

Your choices

  • A: 40
  • B: 42
  • C: 44
  • D: 72
Need a hint?

Write the gaps between the numbers underneath. Do the gaps make a pattern?

Did you know? When coders spot a pattern, they can write a loop: a few lines of code that repeat the rule as many times as they like. The answer page shows this pattern as real Python code!

For teachers and grown-ups

Skills practised: Pattern recognition, abstraction, and predicting the next step of a rule.

The big idea: Spotting a pattern lets a programmer replace lots of repeated steps with one short loop.

Questions to ask:

  • What is the rule, in your own words?
  • How many items repeat before the pattern starts again?
  • What would the 20th item be? How could you work it out without drawing them all?

Take it further: Children invent their own pattern with a hidden rule and challenge a partner to find it.