Tallinn, Nanjing, Kennedy, Cayenne
2
40, the amount of letters in the word, 5, times the number of letters subtracted by one, 4, times the number of letters in the new combination, 2.
6
What_two_japanese_cities_did_the_Allies_drop_the_atomic_bomb_on
2
2
2
There are 24 ways (4 times 3 times 2 times 1) to put 4 different letters in order.
54
Do you mean which US states have 10 letters?CaliforniaWashington
chocolate = 9 letters, where o and c are repeated 2 times. There are 9!/(2!2!) = 90,720 ways.