What Comes Next? #391

Pattern puzzle 391 card

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

Coders spot patterns so they can write loops instead of doing the same thing over and over. Try this one.

Pattern: 2, 6, 18, 54, 162, 486, then a question mark. Choices: A: 1461; B: 1458; C: 1468; D: 2916.
What comes next: A, B, C or D?

The pattern in words: 2, 6, 18, 54, 162, 486, and then… what?

Your choices

  • A: 1461
  • B: 1458
  • C: 1468
  • D: 2916
Need a hint?

Divide each number by the one before it. What do you get?

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.