Numsprite數靈精Play free
中文

Maths olympiad question · P1–P2★ Easy

Cycles: olympiad question 1

An easy question on cycles for P1–P2, with a step-by-step solution, diagrams and the answer. Cycle questions appear in the Hua Xia Cup from the P1 first round to the P5 papers: which comes in a given place, which day of the week, which last digit.

The question

Ming writes the numbers 1, 2, 3 in order, over and over:

1, 2, 3, 1, 2, 3, …

What is the 23rd number he writes?

Show the hints (2)
  1. Hint 1: After how many numbers does it start again from 1?
  2. Hint 2: Split the numbers into groups of 3. Which group is the 23rd number in, and where in that group?

Worked solution

Have a go first, then read the solution step by step.

  1. 1.Groups of 3, one group to a row: 23 ÷ 3 = 7 remainder 2.
  2. 2.After 7 groups count 2 more — the 2nd of a group: 2.

Answer: 2

Play more like this in Numsprite (unlimited questions, instant marking) →A free maths game: every level free from Easy to Expert (★ to ★★★★), unlimited questions, no download