Answers

1. 0 {the number zero is used only 10 times }
   
2. 59 persons.
   
3. First of all his wife and son should go to the other bank of the river. Let his wife stay there. Son should return to this bank.Then Rajan goes to the other bank. Later Rajan sends his wife from the other bank to this bank. Atlast, wife and son again go to the other bank.
   
4. 5 children.
   
5. 21978 x 4 = 87912. Here 87912 is the reverse form of 21978.
   
6. 99 + 9 =9 DOZEN. The five letter word is 'Dozen'.
   
7. When one corner is cutted off 2 more corners are formed. So five is the answer. {3 + 2 = 5}
   
8. 1961
   
9. Price of the shirt - Rs.84
   Price of the handkerchief -Rs.4
   Difference in price- 84 - 4 = 80
   
10. 200 grams