Problem:
If each of the three operation signs,,,+−×, is used exactly ONCE in one of the blanks in the expression
5_4_6_3
then the value of the result could equal
Answer Choices:
A. 9
B. 10
C. 15
D. 16
E. 19
Solution:
The six permutations of,+- and × yield these results:
5×4+6−3=20+6−3=235×4−6+3=20−6+3=175+4×6−3=5+24−3=265−4×6+3=5−24+3=−165+4−6×3=5+4−18=−95−4+6×3=5−4+18=19
The only result listed is 19.
Answer: E.
The problems on this page are the property of the MAA's American Mathematics Competitions