IGCSE Computer Science Paper 1 Crossword: 1.1 Number Systems (Modules 18–27)
Name:
Date:
Class:
✎
Crossword
Read each clue and write the matching term in the grid. Numbers in brackets show the letters in each word.
1
2
3
4
5
6
7
8
9
Across
- 2. Moves every bit one place ______. The leftmost bit falls off and is lost, and a 0 fills the empty place on the right. In 8 bits, 00000101 becomes 00001010. Word 2 of: _______ ____ _____ (4)
- 4. Add two 8-bit ______ numbers column by column from the right. Carry any 1 to the next column on the left. 1 + 1 = 10, so write 0 and carry 1. Check by adding the denary values. Word 2 of: ______ ________ (8)
- 7. Each left shift multiplies a binary number by 2 and each right shift divides it by 2, so n ______ multiply or divide by 2^n. Bits shifted off the end are lost. Word 2 of: n ______ = 2^n (6)
- 8. Word 1 of the term in 4 Across: ______ ________ (6)
- 9. Shifting by n ______ 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. Word 3 of: _____ n ______ (6)
Down
- 1. A base-16 system that shortens binary. One hex digit stands for four bits, so values are shorter to read, easier to copy without mistakes and quick to convert to and from binary. (11)
- 3. Moves every bit one place ______. The bit at the ______ end is lost and a 0 fills the empty left end. For a positive integer this halves the value (rounded down). Word 2 of: _______ _____ _____ (5)
- 5. An error when an 8-bit addition gives a result over 255. It needs a 9th bit, so the carry out of the leftmost column is lost and the stored result is wrong. (8)
- 6. Word 1 of the term in 2 Across: _______ ____ _____ (7)
- 7. Word 3 of the term in 2 Across: _______ ____ _____ (5)
Answer Key
IGCSE Computer Science Paper 1 · Modules 18–27
1H
2L
E
F
T
X
A
3R
4A
D
D
I
T
I
5O
N
E
G
V
6L
C
H
E
O
7S
H
I
F
T
S
R
G
H
M
F
I
8B
I
N
A
R
Y
9P
L
A
C
E
S
F
L
O
A
T
W
L
Across
2LEFT — Moves every bit one place ______. The leftmost bit falls off and is lost, and a 0 fills the empty place on the right. In 8 bits, 00000101 becomes 00001010. Word 2 of: _______ ____ _____
4ADDITION — Add two 8-bit ______ numbers column by column from the right. Carry any 1 to the next column on the left. 1 + 1 = 10, so write 0 and carry 1. Check by adding the denary values. Word 2 of: ______ ________
7SHIFTS — Each left shift multiplies a binary number by 2 and each right shift divides it by 2, so n ______ multiply or divide by 2^n. Bits shifted off the end are lost. Word 2 of: n ______ = 2^n
8BINARY — Word 1 of the term in 4 Across: ______ ________
9PLACES — Shifting by n ______ 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. Word 3 of: _____ n ______
Down
1HEXADECIMAL — A base-16 system that shortens binary. One hex digit stands for four bits, so values are shorter to read, easier to copy without mistakes and quick to convert to and from binary.
3RIGHT — Moves every bit one place ______. The bit at the ______ end is lost and a 0 fills the empty left end. For a positive integer this halves the value (rounded down). Word 2 of: _______ _____ _____
5OVERFLOW — An error when an 8-bit addition gives a result over 255. It needs a 9th bit, so the carry out of the leftmost column is lost and the stored result is wrong.
6LOGICAL — Word 1 of the term in 2 Across: _______ ____ _____
7SHIFT — Word 3 of the term in 2 Across: _______ ____ _____