1) 8+ 8 + 8 + 8 + 8 = _______.
The expression represents repeated addition.  here 8 is added 5 times.
8 + 8 + 8 + 8 + 8 = 8 x 5 = 40.

2)  52 x 1 = ______.
52 x 1 = 52 ( since the product of any number with 1 gives the same number ).

3) 21 x 10 = _______.

21 x 10 = 210.  When we multiply a number  by 10, we add a zero at right of the number  of get the product.

4) Raju bought  9 pencils.  The price of one pencil is 3 rupees.  Find the price of 9 pencils ?
   Price of one pencil = Rs. 3
   Number of pencils = 9
   Price of a pencils = 9 x 3
                              = Rs. 27. 

5) Rekha has one  5 rupee coin in her hand.  To make 15 rupees, she need ____ coins.
We know that  5 x 5 x 5 = 15
she has one 5 rupee coin.
So two  5 rupee coins are needed to make 15 rupees.

6) Multiply  95 x 9 = _______.
 95 x 9 = 855
   

7)  232 x 6 = ______. 
232 x 6 = 1392.

8)  If the cost of one book is Rs. 45.  Find the cost of 8 such books ?
cost of one book = Rs. 45.
cost of 8 books = 8 x 45
                        = Rs. 360.
   

9)  3, 6, 9, _____ find the next number  of the sequence.
Here   3 x 1 = 3
          3 x 2 = 6
          3 x 3 = 9 
So the next number is obtained by multiplying  3 and 4
that is 3 x 4 = 12. 

10)   126 x 3 + 47 x 2 = _______.
126  x 3 = 378
47 x 2 = 94
 126 x 3 + 47 x 2 = 378 + 94 = 472.