1987 AHSME Problems/Problem 3

Revision as of 17:40, 23 April 2017 by Slackroadia (talk | contribs) (Problem)

Problem

How many primes less than $100$ have $7$ as the ones digit? (Assume the usual base ten representation)

$\text{(A)} \ 4 \qquad  \text{(B)} \ 5 \qquad  \text{(C)} \ 6 \qquad  \text{(D)} \ 7 \qquad  \text{(E)} \ 8$

Solution

List out all numbers that have 7 as the ones digit less than 100; ${7, 17, 27, 37, 47, 57, 67, 77, 87, 97}$. Only $7, 17,37, 47,67,$ and $97$ are prime. Thus, it is $\boxed{C}$. -slackroadia

See also

1987 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 2
Followed by
Problem 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
All AHSME Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png