Factors

Q.

The H.C.F. of two numbers is 23 and the other two factors of their L.C.M. are 13 and 14. The larger of the two numbers is

1. 276

2. 322

3. 345

4. 299

Q.

What is the HCF of smallest prime number and the smallest composite number?

Q.

How many prime numbers are there below 100?

1. 20
2. 25
3. 21
4. 29

Q.

HCF of co-prime numbers $4$ and $15$ was found as follows by factorisation: $4=2\times 2$ and $15=3\times 5$ since there is no common prime factor, so HCF of $4$ and $15$ is $0$. Is the answer correct? If not, what is the correct HCF?

Q.

Write the first common multiple of $4$ and $5$.

Q. Which number is neither a prime number nor a composite number?

Q. Which of the following is the prime factor of all the even numbers?

1. 1
2. 2
3. 4
4. 0

Q. The largest factor of a number is ___

1. 3
2. 7
3. Number itself
4. 1

Q. Which of the following are pairs of co-primes?
(i) 8, 14
(ii) 4, 5
(iii) 17, 19
(iv) 27, 15

Q. ___ is a pair of co-prime numbers.

1. 7, 15
2. 22, 48
3. 12, 15
4. 24, 36

Q.

Which of the following is a factor of 15 but not a factor of 12?

1. 
2. 
3. 
4. 

Q.

Find first three common multiples of $3$and $4$.

Q.

Find all common multiples of$4$ and $5$ till $100$.

Q.

Fill in the blanks.

$7\times 8=56$, $7$ and $8$ are________of $56$.

Q. The number 4a6 is divisible by 3. Find the least value of a.

1. 0
2. 2
3. 7
4. 4

Q.

A factor of a number or an expression is always divisible by the number or expression.

1. True

2. False

Q. Evaluate :
iii) $0.3\times (0.5{)}^2$

Q.

What is the HCF of any two co-primes?

Q.

What is a factor of a number? [1 MARK]

Q.

The prime factors of 48 is written as $48=2\times 2\times 2\times$ ___ $\times 3$. Find the missing number.

1. 2

2. 3

3. 4

4. 5

Q. Compute the H.C.F of the pairs of numbers and sort the pairs in ascending order of their H.C.F.

1. 3, 5
2. 6, 8
3. 3, 9
4. 10, 15

Q. The number of factors and multiples of 30 are ____ and ____ respectively.

1. 8, 10
2. 6, infinite
3. 8, infinite
4. infinite, 8

Q.

Two prime numbers are always co-prime.

1. True
2. False

Q.

The L.C.M of 27 and 12 is _________.

1. 96

2. 324

3. 108

4. 36

Q.

Fill in the blanks :

Two numbers having only $1$ as a common factors are called ………. numbers.

Q.

The number _________ has exactly one factor.

Q.

Find all the factors of $32$.

Q. The number which is a factor of all the numbers, is also the smallest _____ number.

1. integer
2. natural
3. whole
4. prime

Q.

Check whether $3216345$ is divisible by $11$or not.

Q.

$a{b}^2$ is a factor of $4a{b}^3-a{b}^2+a{b}^5$.

1. True

2. False