A certain stock exchange designates each stock with a 1, 2 or 3 letter code, where each letter is selected from the 12 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order, constitute a different code, how many diff stocks is it possible to designate with these codes?
Choose one:	A) 2000	B) 1900	C) 1800	D) 1884	E) 1600
Pretty simple actually   Number of 1 letter symbols = 12   Number of 2 letter symbols = 12*12   Number of 3 letter symbols = 12*12*12   The answer is sum of the 3. = 12 +12*12 + 12*12*12 = 12*(1+12+144) =12*157= 
<gadget id="calculator">12*157</gadget>
<output>1_884</output>
1884   So the answer is 1884.
<result>D</result>
A certain stock exchange designates each stock with a 1, 2 or 3 letter code, where each letter is selected from the 12 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order, constitute a different code, how many diff stocks is it possible to designate with these codes?