cannot be expressed as a ratio of two integers, so it is irrational.
Incorrect! Try again.
3Which number is divisible by ?
Divisibility rules
Easy
A.124
B.215
C.421
D.327
Correct Answer: 327
Explanation:
The sum of the digits of is , which is divisible by .
Incorrect! Try again.
4A number is divisible by if its last digit is:
Divisibility rules
Easy
A.6 or 8
B.2 or 4
C.0 or 5
D.1 or 3
Correct Answer: 0 or 5
Explanation:
A whole number is divisible by when its last digit is or .
Incorrect! Try again.
5What is the value of ?
Factorials
Easy
A.12
B.8
C.36
D.24
Correct Answer: 24
Explanation:
.
Incorrect! Try again.
6What is the value of ?
Factorials
Easy
A.1
B.0
C.Undefined
D.2
Correct Answer: 1
Explanation:
By definition, .
Incorrect! Try again.
7What is the unit digit of ?
Unit digit calculation
Easy
A.3
B.7
C.5
D.9
Correct Answer: 7
Explanation:
The unit digit is the last digit of a number, so the unit digit of is .
Incorrect! Try again.
8What is the unit digit of ?
Unit digit calculation
Easy
A.8
B.2
C.6
D.4
Correct Answer: 6
Explanation:
, whose unit digit is .
Incorrect! Try again.
9How many positive factors does have?
Number of factors
Easy
A.5
B.8
C.4
D.6
Correct Answer: 6
Explanation:
The positive factors of are and , giving factors.
Incorrect! Try again.
10Which number has exactly two positive factors?
Number of factors
Easy
A.8
B.15
C.1
D.11
Correct Answer: 11
Explanation:
A number with exactly two positive factors is prime. The number is prime.
Incorrect! Try again.
11What is the remainder when is divided by ?
Remainder theorem
Easy
A.2
B.3
C.4
D.1
Correct Answer: 2
Explanation:
, so the remainder is .
Incorrect! Try again.
12If a number is divided by and leaves a remainder of , which statement is correct?
Remainder theorem
Easy
A.The number is divisible by
B.The number is less than a multiple of
C.The number is more than a multiple of
D.The number is a multiple of
Correct Answer: The number is more than a multiple of
Explanation:
A remainder of means the number can be written as , so it is more than a multiple of .
Incorrect! Try again.
13What is the HCF of and ?
HCF and LCM
Easy
A.9
B.2
C.6
D.3
Correct Answer: 6
Explanation:
The greatest common factor of and is .
Incorrect! Try again.
14What is the LCM of and ?
HCF and LCM
Easy
A.12
B.24
C.10
D.8
Correct Answer: 12
Explanation:
The smallest positive number divisible by both and is .
Incorrect! Try again.
15What is the average of , , and ?
Average calculations
Easy
A.6
B.5
C.7
D.8
Correct Answer: 6
Explanation:
Average .
Incorrect! Try again.
16The average of numbers is . What is their total?
Average calculations
Easy
A.100
B.15
C.40
D.50
Correct Answer: 50
Explanation:
Total .
Incorrect! Try again.
17In a class, students like tea, like coffee, and like both. How many students like tea or coffee?
Inclusion and exclusion
Easy
A.25
B.35
C.40
D.30
Correct Answer: 30
Explanation:
Using inclusion and exclusion, total .
Incorrect! Try again.
18In a group of people, like cricket and like football. If like both, how many like at least one of the two sports?
Inclusion and exclusion
Easy
A.30
B.43
C.23
D.33
Correct Answer: 33
Explanation:
People liking at least one sport .
Incorrect! Try again.
19A student scores in a test worth and in a test worth . What is the weighted average?
Weighted average
Easy
A.76
B.74
C.72
D.78
Correct Answer: 76
Explanation:
Weighted average .
Incorrect! Try again.
20A shop mixes kg of rice at per kg with kg at per kg. What is the average price per kg?
Weighted average
Easy
A.$36
B.$34
C.$38
D.$40
Correct Answer: $36
Explanation:
Average price per kg.
Incorrect! Try again.
21Which type of number is ?
Classification of numbers
Medium
A.A rational integer
B.A rational non-integer
C.A non-real number
D.An irrational number
Correct Answer: An irrational number
Explanation:
, which is irrational.
Incorrect! Try again.
22Which of the following expressions represents a rational number?
Classification of numbers
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
, so it is rational. The other expressions are irrational.
Incorrect! Try again.
23What is the smallest digit such that the number is divisible by ?
Divisibility rules
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The digit sum is . The smallest value making this a multiple of is .
Incorrect! Try again.
24Which digit should replace in so that the number is divisible by ?
Divisibility rules
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The alternating-sum difference is . For divisibility by , this must equal , giving .
Incorrect! Try again.
25How many trailing zeros are present in ?
Factorials
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The numbers of factors of are in and in . Their difference is .
Incorrect! Try again.
26What is the highest exponent of that divides ?
Factorials
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The exponent is .
Incorrect! Try again.
27What is the unit digit of ?
Unit digit calculation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The unit digits of powers of repeat as . Since leaves remainder when divided by , the unit digit is .
Incorrect! Try again.
28What is the unit digit of ?
Unit digit calculation
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
has unit digit , while has unit digit . Their sum has unit digit .
Incorrect! Try again.
29How many positive factors does have?
Number of factors
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , its number of factors is .
Incorrect! Try again.
30How many positive divisors of are perfect squares?
Number of factors
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
. A square divisor uses even exponents, giving choices for , for , and for . Thus there are .
Incorrect! Try again.
31What is the remainder when is divided by ?
Remainder theorem
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Powers of modulo repeat as . Since leaves remainder when divided by , the remainder is .
Incorrect! Try again.
32What is the remainder when is divided by ?
Remainder theorem
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
By the remainder theorem, substitute : .
Incorrect! Try again.
33Two positive integers have HCF and LCM . If one integer is , what is the other integer?
HCF and LCM
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The product of the integers equals the product of their HCF and LCM. Thus the other integer is .
Incorrect! Try again.
34Two numbers are in the ratio , and their HCF is . What is their LCM?
HCF and LCM
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since and are coprime, the numbers are and . Their LCM is .
Incorrect! Try again.
35The average of numbers is . If one of the numbers, , is removed, what is the average of the remaining numbers?
Average calculations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The original total is . After removing , the new average is .
Incorrect! Try again.
36The average of numbers increases by when the number is replaced. What is the new number?
Average calculations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
An increase of in the average raises the total by . Therefore, the new number is .
Incorrect! Try again.
37In a group of students, study Mathematics, study Science, and study both. How many study neither subject?
Inclusion and exclusion
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The number studying at least one subject is . Therefore, study neither.
Incorrect! Try again.
38Among students, join club , join club , and join club . Also, join both and , join both and , join both and , and join all three. How many join at least one club?
Inclusion and exclusion
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
By inclusion-exclusion, the total is .
Incorrect! Try again.
39A class has students with an average score of and students with an average score of . What is the average score of the entire class?
Weighted average
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The weighted average is .
Incorrect! Try again.
40A merchant mixes kg of rice costing per kg with kg of rice costing per kg. What is the average cost per kg of the mixture?
Weighted average
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The total cost is . Dividing by the total weight gives per kg.
Incorrect! Try again.
41Classify the number .
Classification of numbers
Hard
A.An irrational algebraic number
B.A rational non-integer
C.A transcendental real number
D.A rational integer
Correct Answer: An irrational algebraic number
Explanation:
Since , the fourth power is . Therefore, the expression equals , which is irrational and algebraic.
Incorrect! Try again.
42If the six-digit number is divisible by both and , find .
Divisibility rules
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Divisibility by gives . Divisibility by gives , so . Hence , giving and . Thus .
Incorrect! Try again.
43What is the greatest integer such that divides ?
Factorials
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , calculate and . Therefore, .
Incorrect! Try again.
44Find the unit digit of .
Unit digit calculation
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The cycles have length . Since , the unit digits are , , and , respectively. Their sum is , whose unit digit is .
Incorrect! Try again.
45Find the smallest positive multiple of having exactly positive divisors.
Number of factors
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
, so it has divisors. Checking smaller multiples of shows their divisor counts are , , , , and , so is the first valid multiple.
Incorrect! Try again.
46Find the remainder when is divided by .
Remainder theorem
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Modulo , we have . Thus and , giving .
Incorrect! Try again.
47Two positive integers have HCF and LCM . If one of them is , find the other.
HCF and LCM
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For two positive integers and , . Hence the other number is .
Incorrect! Try again.
48The average of numbers is . Two numbers, and , are replaced by and , respectively. The new average is , and . Find .
Average calculations
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The total increase is . Therefore, , so . Solving and gives .
Incorrect! Try again.
49How many integers from to are divisible by at least one of , , and , but not divisible by ?
Inclusion and exclusion
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The union count is . Removing the multiples of gives .
Incorrect! Try again.
50The average score of students is , and that of another students is . What average must additional students obtain for the overall average of all students to be ?
Weighted average
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The first two groups contribute . The required total is . Thus, the additional students must score , giving an average of .
Incorrect! Try again.
51Classify the number .
Classification of numbers
Hard
A.A rational non-integer
B.A transcendental number
C.An irrational algebraic number
D.A rational integer
Correct Answer: An irrational algebraic number
Explanation:
Squaring the expression gives . Hence the number is , which is irrational and algebraic.
Incorrect! Try again.
52Find the sum of all numbers of the form that are divisible by .
Divisibility rules
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Divisibility by requires to be divisible by , giving or . Divisibility by then gives or . The numbers are and , whose sum is .
Incorrect! Try again.
53How many trailing zeroes does have?
Factorials
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The exponent of in is , while in it is . The exponent of is larger, so the number of trailing zeroes is .
Incorrect! Try again.
54Find the unit digit of .
Unit digit calculation
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For exponent , the unit digits are and . Their sum is , so the unit digit is .
Incorrect! Try again.
55How many positive divisors of are perfect squares and divisible by ?
Number of factors
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For a square divisor, exponents must be even. The allowed exponents are for , for , and for . Therefore, the count is .
Incorrect! Try again.
56Find the remainder when is divided by .
Remainder theorem
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
By the remainder theorem, substitute . The resulting geometric sum is .
Incorrect! Try again.
57Find the least positive integer such that , , , and .
HCF and LCM
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The first three conditions imply . Requiring divisibility by gives , so . The least value is .
Incorrect! Try again.
58The average of values is . If the first values are increased by each and the remaining values are decreased by each, what is the new average?
Average calculations
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The total change is . The average increases by , so the new average is .
Incorrect! Try again.
59In a group of students, study Mathematics, study Physics, and study Chemistry. Exactly , , and study Mathematics and Physics, Physics and Chemistry, and Chemistry and Mathematics, respectively. If study all three subjects, how many study exactly one subject?
Inclusion and exclusion
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The number studying exactly one subject is .
Incorrect! Try again.
60A mixture contains substance at concentration , substance at concentration , and the remaining portion at concentration . If the mixture concentration is , find .
Weighted average
Hard
A.
B.
C.$94.8\%
D.
Correct Answer: $93.6\%
Explanation:
Using the weighted average, . Thus, , giving .
Incorrect! Try again.
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