AMO 2018 — Primary 4 (Grade 4) Question 19

Kenneth writes the whole numbers in order as shown below. The 1st number in Row 1 is 1. The 1st and 2nd number in Row 2 are 2 and 3, respectively, and so on. What is the 27th number in Row 27?

Row 1: 1

Row 2: 2 3

Row 3: 4 5 6