EASY
Earn 100

Write all the prime numbers between 1 and 20.

Important Questions on Playing with Numbers

EASY
Calculate the total number of prime factors in the expression:

911×57×75×32×172

MEDIUM
How many positive factors of 24 are there?
MEDIUM

Which of the following statement(s) is/are true?

I. There are 12 multiples of 9 from 7 to 109.

II. There are 9 multiples of 13 from 19 to 119.

EASY
One of the factors of 82k+52k, where k is an odd number, is:
EASY

The total number of factors of 1156 is: 

(A) 9 

(B) 8 

(C) 10 

(D) 11 

EASY
How many positive factors of 68 are there?
MEDIUM

Consider the number N=126×38×53. Which of the following statements is/are correct?

1. The number of odd factors of N is 60.

2. The number of even factors of N is 720.

Select the correct answer using the code given below:

EASY

The sum of all the factors of 156 is: 
(A) 392
(B) 235
(C) 390
(D) 379

EASY

The prime factorisation of 240 is:

(A) 23×32×5 

(B) 24×32×5

(C) 24×3×5

(D) 25×3×5

 

EASY
The number of prime numbers which are less than 100 is:
MEDIUM

What is the number of Prime factor in 1518×410×69.

EASY
Consider the pairs of prime numbers (m, n) between 50 and 100 such that m-n=6. How many such pairs are there?
MEDIUM
When 732 is divided by a positive integer x, the remainder is 12. How many values of x are there?
MEDIUM
One fourth of the sum of the prime numbers, greater than 4 but less than 16, is the square of
EASY
Find the mean of the first 6 prime numbers.
MEDIUM

Consider the following statements in respect of all factors of 360:

1. The number of factors is 24.

2. The sum of all factors is 1170.

Which of the above statements is/are correct?

EASY
Which of the following is not a pair of prime numbers ?
EASY
The sum of the squares of the digits of the largest two-digit prime number is:
EASY
Which of the following number is an odd and prime number?