4.4: Arithmetic Shift
Eduqas / WJEC
What is arithmetic shift?
Arithmetic shift is used to multiply and divide binary numbers.
The effect of shifting left is to multiply a binary number.
The effect is doubled by each place that is shifted.
The effect of shifting right is to divide a binary number.
Shifting by 1 has an effect of 2.
Shifting by 2 has an effect of 4.
Shifting by 3 has an effect of 8.
For example, shifting left by 2 places has an effect of multiplying by 4.
Another example: Shifting right by 3 places has an effect of diving by 8.
How to shift a binary number:
An exam question may ask you to arithmetically shift a binary number of up to 16 digits.
4.4 - Arithmetic Shift:
1a. Draw a diagram to show the effect of multiplying and dividing a binary number. 
1b. Draw a diagram or table to show the effect a shift has for each place from 1 to 4. For example, a shift of 1 place has an effect of 2. 
2. State the effect of the following shifts:
a. Shift right by 2 places.
b. Shift left by 1 place.
c. Shift left 3 places.
d. Shift right by 4 places. [1 each]
3. Shift the following binary numbers and state the effect of the shift:
a. 10101011 : Shift left by 2 places.
b. 11101100 : Shift right by 3 place.
c. 00001011 : Shift right by 2 places.
d. 01101110 : Shift left by 1 place. [2 each]