Logical left shift
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. After a logical left shift, what fills the empty place on the right?
2. Which direction does every bit move in a logical left shift?
3. What happens to the leftmost bit when you do a logical left shift?
4. What is 00000101 after one logical left shift in 8 bits?
5. What is 11000011 after one logical left shift in 8 bits?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 100000101 << 1 = 00001010 | A00010111 << 1 = 00101110 | |
| 211000011 << 1 = 10000110 | B10110001 << 1 = 01100010 | |
| 3Zeros come in on the right: after a left shift, the empty right-hand place is filled with 0. | CA logical left shift by one place: every bit moves one place left and a 0 fills the empty right end. | |
| 4Bits shifted off the left end are lost: the leftmost bit is dropped and cannot be recovered. | DThe empty place on the right was filled with 1. A logical left shift always fills it with 0, so the answer should be 01100110. | |
| 500000101 << 1 = 10000010 | EThis is a right shift result. In a left shift the bits move left and a 0 fills the right end, so the answer should be 00001010. | |
| 600110011 << 1 = 01100111 | FThe leftmost 1 falls off the end and is lost, and a 0 enters on the right. |
C
Definitions
logical left shift
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
Logical ____ shift: 00000101 -> 00001010
2.
00000101 __ 1 = 00001010
3.
11000011 << 1 = 1000011_
4.
00000011 << _ = 00001100
5.
10000001 << 1 = ________
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
Register: 0000101
B
Shift left by 1 place
C
Drop the leftmost bit: 0
D
Add 0 on the right
E
Result: 00001010
Question 2
A
x = 00000011
B
x = x >> 1
C
# bits move one place left
D
# 0 enters on the right
E
# x is now 00000110
Question 3
A
Start: 00010110
B
Shift left 1 place
C
Leftmost bit 0 goes to right
D
New right bit is 0
E
Result: 00101100
Question 4
A
Start: 11000001
B
Shift left 1 place
C
Leftmost 1 is dropped
D
New right bit is 1
E
Result: 10000010
Question 5
A
n = 00000100
B
n = n << 2
C
print(n)
D
# shifted left by 1, 00001000
Answer Key
Logical left shift
Section A: Quick Questions
Q1
B — A 0
Q2
B — One place to the left
Q3
A — It falls off the end and is lost
Q4
A — 00001010
Q5
A — 10000110
Section B: Match the Pairs
Q1
00000101 << 1 = 00001010 → A logical left shift by one place: every bit moves one place left and a 0 fills the empty right end.
Q2
11000011 << 1 = 10000110 → The leftmost 1 falls off the end and is lost, and a 0 enters on the right.
Q3
Zeros come in on the right: after a left shift, the empty right-hand place is filled with 0. → 00010111 << 1 = 00101110
Q4
Bits shifted off the left end are lost: the leftmost bit is dropped and cannot be recovered. → 10110001 << 1 = 01100010
Q5
00000101 << 1 = 10000010 → This is a right shift result. In a left shift the bits move left and a 0 fills the right end, so the answer should be 00001010.
Q6
00110011 << 1 = 01100111 → The empty place on the right was filled with 1. A logical left shift always fills it with 0, so the answer should be 01100110.
Section C: Definitions
Q1
logical left shift — Moves every bit one place left. The leftmost bit falls off and is lost, and a 0 fills the empty place on the right. In 8 bits, 00000101 becomes 00001010.Section D: Fill in the Blanks
Q1
Logical left shift: 00000101 -> 00001010Q2
00000101 << 1 = 00001010Q3
11000011 << 1 = 10000110Q4
00000011 << 2 = 00001100Q5
10000001 << 1 = 00000010Section E: Spot the Error
Q1
A — An 8-bit register holds exactly 8 bits. 0000101 has only 7 bits. The register should be 00000101.
Q2
B — << is the left shift operator. >> shifts right. The line should be x = x << 1.
Q3
C — In a logical left shift the leftmost bit is dropped and lost. It does not wrap round to the right. The line should say the leftmost bit 0 is dropped.
Q4
D — A logical left shift always fills the empty right-hand place with 0, never 1. The line should say the new right bit is 0.
Q5
B — Shifting 00000100 left by 1 place gives 00001000. << 2 would shift two places and give 00010000. The line should be n = n << 1.