UKMT - Senior Mathematical Challenge - 2021 - 2 | Exact Science

2

The sequence of primes rounded to the nearest ten begins 0, 0, 10, 10, 10, 10, 20, 20. How many terms are equal to 40?

A. 1 B. 2 C. 3 D. 4 E. 5

Answer

C

SOLUTIOn

Primes between 35 and 44 (37, 41, 43) round to 40, giving three terms of 40.

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