MathDB

18

Part of 2006 AMC 10

Problems(2)

License plates.

Source: AMC 10 2006A, Problem 18

2/6/2006
A license plate in a certain state consists of 4 digits, not necessarily distinct, and 2 letters, also not necessarily distinct. These six characters may appear in any order, except that the two letters must appear next to each other. How many distinct license plates are possible? <spanclass=latexbold>(A)</span>104262<spanclass=latexbold>(B)</span>103263<spanclass=latexbold>(C)</span>5104262<spanclass=latexbold>(D)</span>102264<spanclass=latexbold>(E)</span>5103263 <span class='latex-bold'>(A) </span> 10^4\cdot 26^2 \qquad <span class='latex-bold'>(B) </span> 10^3\cdot 26^3 \qquad <span class='latex-bold'>(C) </span> 5\cdot 10^4\cdot 26^2 \qquad <span class='latex-bold'>(D) </span> 10^2\cdot 26^4\\ <span class='latex-bold'>(E) </span> 5\cdot 10^3\cdot 26^3
AMC
Sequences

Source: AMC 10 2006B, Problem 18

2/17/2006
Let a1,a2,... a_1, a_2, ... be a sequence for which a_1 \equal{} 2\,\hspace{.2in}a_2 \equal{} 3\, \hspace{.2in}\text{and}\hspace{.2in}a_n \equal{} \frac {a_{n \minus{} 1}}{a_{n \minus{} 2}} \text{ for each positive integer } n \ge 3.What is a2006 a_{2006}?
<spanclass=latexbold>(A)</span>12<spanclass=latexbold>(B)</span>23<spanclass=latexbold>(C)</span>32<spanclass=latexbold>(D)</span>2<spanclass=latexbold>(E)</span>3<span class='latex-bold'>(A) </span> \frac 12 \qquad <span class='latex-bold'>(B) </span> \frac 23 \qquad <span class='latex-bold'>(C) </span> \frac 32 \qquad <span class='latex-bold'>(D) </span> 2 \qquad <span class='latex-bold'>(E) </span> 3
AMC