1973 AMC 12 Problem 31

Attempt Problem 31 of the 1973 AMC 12 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1973 AMC 12 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

31.

In the following equation, each of the letters represents uniquely a different digit in base ten: (YE)(ME)=TTT. (YE)\cdot(ME)=TTT. The sum E+M+T+YE+M+T+Y equals

1919

2020

2121

2222

2424

Answer: C
Concepts:cryptarithmdivisibilitydigitsunits digit
Difficulty rating: 2190
Small Hint:

Use TTT=111T=337TTTT=111T=3\cdot37\cdot T

Big Hint:

The prime 3737 must divide one of the two-digit factors; test its two-digit multiples ending in the common digit EE

Solution:

Since TTT=111T=337T, TTT=111T=3\cdot37\cdot T, the prime 3737 divides one of YEYE and ME.ME. A two-digit multiple of 3737 is 3737 or 74.74. The value 7474 is impossible: the other two-digit factor ending in 44 is at least 14,14, and 7414>999.74\cdot14\gt999. Hence one factor is 37,37, so E=7.E=7.

The units digit of the product is the units digit of 72,7^2, so T=9.T=9. Thus the product is 999,999, and the other factor is 99937=27. \frac{999}{37}=27. The four digits are 2,2, 3,3, 7,7, 9,9, whose sum is 21.21.

Therefore, the correct answer is C.

← Problem 30#30
Full Exam

Problem 31 in Other Years

1950 AMC 12 · 1951 AMC 12 · 1952 AMC 12 · 1953 AMC 12 · 1954 AMC 12 · 1955 AMC 12 · 1956 AMC 12 · 1957 AMC 12 · 1958 AMC 12 · 1959 AMC 12 · 1960 AMC 12 · 1961 AMC 12 · 1962 AMC 12 · 1963 AMC 12 · 1964 AMC 12 · 1965 AMC 12 · 1966 AMC 12 · 1967 AMC 12 · 1968 AMC 12 · 1969 AMC 12 · 1970 AMC 12 · 1971 AMC 12 · 1972 AMC 12