Library / UKMT Intermediate Mathematical Challenge /21 of 267

UKMT Intermediate Mathematical Challenge, 2021

Number theory Difficulty 1.0 Junior Find the answer United Kingdom

The prime factor decomposition of 2021 is $43 \times 47$ . What is the value of $53 \times 57$ ?

(A) $2221$ (B) $2521$ (C) $2921$ (D) $3021$ (E) $3031$

We don't reproduce this publisher's solutions. Their own solution is here — work the problem first.

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: UK Mathematics Trust, licensed © UK Mathematics Trust; past papers published free at ukmt.org.uk. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.