Difference between revisions of "1973 AHSME Problems/Problem 31"

(Solution to Problem 31)
 
(See Also)
 
Line 20: Line 20:
  
 
==See Also==
 
==See Also==
{{AHSME 35p box|year=1973|num-b=30|num-a=32}}
+
{{AHSME 30p box|year=1973|num-b=30|num-a=32}}
  
 
[[Category:Introductory Number Theory Problems]]
 
[[Category:Introductory Number Theory Problems]]

Latest revision as of 13:04, 20 February 2020

Problem

In the following equation, each of the letters represents uniquely a different digit in base ten:

\[(YE) \cdot (ME) = TTT\]

The sum $E+M+T+Y$ equals

$\textbf{(A)}\ 19 \qquad \textbf{(B)}\ 20 \qquad \textbf{(C)}\ 21 \qquad \textbf{(D)}\ 22 \qquad \textbf{(E)}\ 24$

Solution

The right side of the equation can be rewritten as $111T = 37 \cdot 3T$. With trial and error and prime factorization as a guide, we can test different digits of $T$ to see if we can find two two-digit numbers that have the same units digit and multiply to $111T$.

The only possibility that works is $37 \cdot 27 = 999$. That means $E+M+T+Y = \boxed{\textbf{(C)}\ 21}$.

See Also

1973 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 30
Followed by
Problem 32
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 31 32 33 34 35
All AHSME Problems and Solutions