1
QUESTIONS:
1.
The value of 10
1 ,
1 ×
is
A 1 B 11
C 1,1 D 11,1
E 110
ANSWER: B EXPLANATION:
x
10 means the original number becomes ten times larger. Move the decimal comma one place to the right.
2.
4 2
3 2
÷ is equal to
A 2 B 3
C 4 D 16
E 32
ANSWER: D EXPLANATION:
3 2
4 4 4 4
2 2 2
64 4
64 16
4
= × × = ×
= =
∴ =
3. Did you know?
In the decimal number system base 10 ten different digits, 0 to 9, are used to write all the numbers. In the binary number
system base 2 two different digits are used, i.e. 0 and 1. Which one of the following numbers is not a valid number in the octal
number system base 8? A
B C
D E
128 127
126 125
124 ANSWER: A
EXPLANATION: When working in base 2: numbers are written in terms of 0 and 1;
When working in base 3: we use 0, 1 and 2; When working in base 4: we use 0, 1, 2 and 3;
When working in base 5: we use 0, 1, 2, 3 and 4; When working in base 10: we use 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9;
and so on.
When working in base 8: we use 0, 1, 2, 3, 4, 5, 6 and 7.
2
4.
At a recent Athletics Championship Sipho broke the old record of 11,01 seconds for the 100 metre race by 0,04 seconds.
The new record for the race in seconds is
A 10,01 B 10, 04
C 10,61 D 11, 05
E 10,97 ANSWER: E
EXPLANATION:
11,01 0,04
10,97 −
5. What is the units digit of 4
2003
? A
B C
D E
2 4
6 8
ANSWER: C EXPLANATION:
1 2
3 4
4 4
4 16
4 64
4 256
= =
= =
All even powers of 4 give a units digit of 6 and all odd powers of 4 give a units digit of 4.
The units digit of 4
2003
will therefore be 4.
3
6.
The following net is given:
Which one of the following cubes cannot be folded from this net?
ANSWER: B EXPLANATION:
Check the distractors:
A: The three visible sides are adjacent as required.
B: The triangle is adjacent to the cross.
C: The three visible sides are adjacent as required.
D: The three visible sides are adjacent as required.
E: The three visible sides are adjacent as required.
B: Not possible from given net because the triangle has
to be opposite the cross. A
B C
D E
4
7.
Susan’s average mark for the four terms numbered 1 to 4 on the horizontal axis of 2002 was 70. The mark for each term is out of
50 and carries the same weight when calculating the average. Use the graph to determine what her percentage was for the first term of 2002.
A equal to or more than 70
B equal to or less than 20
C between 20 and 30
D between 40 and 50
E between 50 and 70
ANSWER: E EXPLANATION:
Average is 70, which is 70 out of 100. For the four terms, the total is therefore 280 out of 400.
Second term:
40 out of 50 equals 80 out of 100 Third term:
25 out of 50 equals 90 out of 100 Fourth term:
45 out of 50 equals 50 out of 100 First term:
280 – 80 + 50 + 90 = 60 out of 100 which is between 50 and 70
5 10
15 25
30 35
40
20 45
50
1 2
3 4
?
Aver age
m ar
k
Terms
5
8.
If 25
20 −
x is expressed in the form
4
a x
b
+ ,
then the value of
b a
+ is
A 20
B 10
C 0 D 10
E 20
− −
ANSWER: C EXPLANATION:
If 20 25
4 4
then 4
20 5
and 25
5 25
5 5 5
x a
x b
ax ab
a a
ab b
b a
b −
= +
= +
= ∴
= = −
∴ = −
∴ = −
∴ + = + − =
9. Did you know?
