Australian AMC 2024 - Middle Primary Question 24

The stairs in Bernard’s building are numbered 1, 2, 3, … . When he climbs them, he always starts by taking them two at a time, as shown below on the left. After doing this 10 times, he is tired and he takes the next 10 stairs one at a time. Then he goes back to 10 double steps, then 10 single steps, and so on. Which of the following numbers will Bernard not step on?



The labels “start” and “tired” identify the two walking patterns.