Sunday Times Teaser 2979 – Mischievous Sam
by Graham Smithers
Published October 27 2019 (link)
I set Sam a question, the answer to which was a 3-digit number, with the digits increasing by 1 from first to last (eg 789)
Sam eventually produced a 3-digit answer, but only 2 of his digits were correct and in the correct position. The third digit was wrong.
Investigating further I found that Sam had the correct answer but, for devilment, decided to change it into a different (single-digit) base.
If I were to tell you which of his 3 digits was the wrong one, you should be able to tell me:
(a) the correct answer, and
(b) the base used by Sam.