In the Land of Oz only one or two-letter words are used. The local language has 67 different letters. The parliament decided to forbid the use of the seventh letter. How many words have the people of Oz lost because of the prohibition?	Select:
A) 65  B) 66  C) 67  D) 131  E) 134
The answer to the question is indeed E. The problem with above solutions is that they do not consider words like AA, BB, ...   The number of 1 letter words (X) that can be made from 67 letters is 67;   The number of 2 letter words (XX) that can be made from 67 letters is 67*67, since each X can take 67 values.   Total: 67+67*67.   Similarly:   The number of 1 letter words (X) that can be made from 66 letters is 66;   The number of 2 letter words (XX) that can be made from 66 letters is 66*66, since each X can take 66 values.   Total: 66+66*66.   The difference is (67+67*67)-(66+66*66)= 
<gadget id="calculator">(67+67*67)-(66+66*66)</gadget>
<output>134</output>
134.   Answer: 134.
<result>E</result>
In the Land of Oz only one or two-letter words are used. The local language has 67 different letters. The parliament decided to forbid the use of the seventh letter. How many words have the people of Oz lost because of the prohibition?