A good answer might be:

Multiply 9910 times 9910 : 9801

How many decimal places does each operand (99) take: 2.

How many decimal places does the result take: 4.

Twice the Number of Places

The product of two N-place decimal integers may need 2N places. This is also true for numbers expressed in any base. In particular, the product of two integers expressed with N-bit binary may need 2N bits. For example, here two 8-bit unsigned integers are multiplied using the usual paper-and-pencil multiplication algorithm (but using binary arithmetic): 

        10110111            B7          18310
        10100010            A2          16210
        --------            --          ---
        00000000
       10110111.
      00000000..
     00000000...
    00000000....
   10110111.....
  00000000......
 10110111.......
 ---------------          ----        -----
 111001111001110          73CE        2964610

The two 8-bit operands result in a 15-bit product. Also shown are the same produce done with base 16 and base 10 notation.

QUESTION 2:

Is a 32-bit general register likely to hold the result of multiplying two other 32-bit registers?