Let p, q, r and s be natural numbers such that
p − 2016 = q + 2017 = r − 2018 = s + 2019
Which one of the following is the largest natural number?
Answer & explanation
Answer: (c) r
Call the common value k. Then each number is k plus or minus a constant, and r = k + 2018 carries the largest addition.
- Let p − 2016 = q + 2017 = r − 2018 = s + 2019 = k.
- Then p = k + 2016, q = k − 2017, r = k + 2018, s = k − 2019.
- The largest is r = k + 2018.
Remember · Set equal expressions to one variable k and compare what is added to k in each.
Question and answer: UPSC's official GS Paper II (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·