Quiz 9.5

DIRECTIONS: Read each question carefully. Then click on the dot next to the answer that most closely fits the question. Try to answer all questions on this quiz and when you are done, click on the grade me button at the bottom.

Coverage: Section 9.8

  1. Multiplication is often difficult for simple computers to do. What is a common shortcut for multiplying numbers by 2 or powers of 2?
shifting the numbers to the left
shifting the numbers to the right
inserting the bits of the numbers into a mask

  1. If we multiply two 8-bit whole numbers, what is the longest product we could ever get?
8 bits
12 bits
16 bits
32 bits

  1. One of the numbers in a multiplication is called the multiplier. What is the other one called?
divisor
subtrahend
multiplexor
multiplicand

  1. What operations are used to implement multiplication, even in algorithms for decimal multiplication that we all learned in grade school?
addition and subtraction
addition and division
addition and shifting
shifting and subtraction

  1. Which of the following pseudo-code algorithms for binary whole number multiplication is correct? 
   while the counter is not equal to 0 do...
        if the msb of multiplier is 0 then
             add the multiplicand to the product
        else add 0 to the product
        shift the multiplier one bit left
        subtract 1 from the counter
        if the counter > 0 then
             shift the product one bit to the left


   while the counter is not equal to 0 do...
        if the msb of multiplier is 1 then
             add the multiplicand to the product
        else add 0 to the product
        shift the multiplier one bit left
        subtract 1 from the counter
        if the counter > 0 then
             shift the product one bit to the left


   while the counter is not equal to 0 do...
        if the msb of multiplier is 1 then
             add the multiplicand to the product
        else add 0 to the product
        shift the multiplier one bit left
        add 1 to the counter
        if the counter > 0 then
             shift the product one bit to the left


   while the counter is not equal to 0 do...
        if the msb of multiplier is 1 then
             add the multiplicand to the product
        else add 0 to the product
        shift the multiplier one bit left
        subtract 1 from the counter
        if the counter >= 0 then
             shift the product one bit to the left

  1. In the following multiplication, the number that controls the addition is 11001101 and the number that gets repeatedly added and shifted is 001010011: 
         11001101 × 00101011 = 0010001001101111
    How many times does addition of a number other than 0 occur?
8
4
5

  1. When examining the multiplier to see whether or not to add the multiplicand, which condition bit is checked?
N
C
V
Z

  1. What is very efficient about the binary multiplication algorithm presented in this section?
it requires a constant number of additions, which is the number of bits in the multiplier
it requires as many additions as the magnitude of the multiplier
it only needs storage for three numbers
it only uses one condition bit

  1. Since multiplication is tedious, even in binary, let's concentrate on multiplying 4-bit numbers. What is the product of the following? 
         1001 × 1101
     --


     1111011

    

     100111

    

     1110101

    

     11101
     --