Multiple shifts
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Logical left shift 00001011 by 2 places. What is the result?
2. Logical right shift 11010000 by 3 places. What is the result?
3. Logical left shift 10110101 by 3 places. What is the result?
4. A left shift by 3 places on an 8-bit value does what?
5. Logical right shift 00000011 by 2 places. What is the result?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 100001011 shifted left 3 places | AThe two leftmost bits (10) were lost, but the 2 bits added on the right were 1s in the wrong places. Added bits must be 0s, so the answer is 11001100 only if the shift is done correctly: the correct result is 11001100, so the error is keeping the lost bits instead of dropping them. | |
| 211010110 shifted right 2 places | B00110101: every bit moves 2 places right, the 2 rightmost bits (10) are lost and 2 zeros are added on the left | |
| 3Shifting an 8-bit number left by 3 places moves each bit 3 positions and adds three 0s at the right-hand end | C01011000: every bit moves 3 places left, the 3 leftmost 0s are lost and 3 zeros are added on the right | |
| 4Shifting all 8 bits out of an 8-bit register leaves only zeros | D00000101 -> 00101000 | |
| 510110011 shifted left 2 places = 11001100 | EZeros must be added on the left, not 1s, and the 3 rightmost bits are lost. The correct result is 00001101. | |
| 601101100 shifted right 3 places = 11101101 | F11111111 shifted right 8 places = 00000000 |
C
Definitions
shift n places
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
Left shift 2: 00000111 becomes ________
2.
Left shift by 3 adds _ zeros on the right
3.
_____ shift 2: 10110100 becomes 00101101
4.
Left shift _: 10110011 becomes 00000000
5.
Right shift 3: 00011000 becomes ________
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
Value: 00001101
B
Operation: left shift by 2
C
Lose 2 leftmost bits: 00
D
Add 2 zeros on left: 00110100
Question 2
A
Start: 10110100
B
Right shift 3: 00101101
C
Lost 3 bits: 100 (from right)
Question 3
A
Right shift by 3 places
B
Start: 00010111
C
Lose 3 bits from the left: 000
D
Result: 10111000
Question 4
A
Start: 01101011
B
Left shift by 4 places
C
All 8 bits are lost
D
Result: 00000000
Question 5
A
Start: 11001110
B
Right shift by 2 places
C
Result: 11110011
D
Lost bits: 10
Answer Key
Multiple shifts
Section A: Quick Questions
Q1
B — 00101100
Q2
A — 00011010
Q3
A — 10101000
Q4
A — Loses 3 bits from the left end and adds 3 zeros on the right
Q5
B — 00000000
Section B: Match the Pairs
Q1
00001011 shifted left 3 places → 01011000: every bit moves 3 places left, the 3 leftmost 0s are lost and 3 zeros are added on the right
Q2
11010110 shifted right 2 places → 00110101: every bit moves 2 places right, the 2 rightmost bits (10) are lost and 2 zeros are added on the left
Q3
Shifting an 8-bit number left by 3 places moves each bit 3 positions and adds three 0s at the right-hand end → 00000101 -> 00101000
Q4
Shifting all 8 bits out of an 8-bit register leaves only zeros → 11111111 shifted right 8 places = 00000000
Q5
10110011 shifted left 2 places = 11001100 → The two leftmost bits (10) were lost, but the 2 bits added on the right were 1s in the wrong places. Added bits must be 0s, so the answer is 11001100 only if the shift is done correctly: the correct result is 11001100, so the error is keeping the lost bits instead of dropping them.
Q6
01101100 shifted right 3 places = 11101101 → Zeros must be added on the left, not 1s, and the 3 rightmost bits are lost. The correct result is 00001101.
Section C: Definitions
Q1
shift n places — Shifting by n places moves every bit n positions, losing n bits at one end and adding n zeros at the other. Shift all 8 bits out and you get 00000000.Section D: Fill in the Blanks
Q1
Left shift 2: 00000111 becomes 00011100Q2
Left shift by 3 adds 3 zeros on the rightQ3
Right shift 2: 10110100 becomes 00101101Q4
Left shift 8: 10110011 becomes 00000000Q5
Right shift 3: 00011000 becomes 00000011Section E: Spot the Error
Q1
D — In a left shift the bits that are lost come off the left, so the new zeros are added on the right, not the left. It should read: Add 2 zeros on right: 00110100.
Q2
B — 00101101 is the result of shifting right by only 2 places. Shifting right by 3 moves every bit 3 places, giving 00010110.
Q3
A — The working loses bits from the left and the result 10111000 is a left shift. The first line should say Left shift by 3 places.
Q4
B — Only a shift of 8 places pushes all 8 bits out of an 8-bit register. A shift by 4 would leave 4 of the original bits behind. It should say Left shift by 8 places.
Q5
C — A logical right shift adds zeros on the left, never ones. Shifting 11001110 right by 2 gives 00110011.