The numbers 13 and 31 are prime numbers. Both these numbers have same digits 1 and 3. Find such pairs of prime numbers upto 100.

The number of distinct prime factors of the smallest 5-digit number is

The sum of the prime factors of 1729 is

The number of distinct prime factors of the largest 4-digit number is

Which of the following numbers are co-prime?

(a) 18 and 35 (b) 15 and 37

(c) 30 and 415 (d) 17 and 68

(e) 216 and 215 (f) 81 and 16

Which of the following numbers are prime?

(a) 23 (b) 51

(c) 37 (d) 26

Give three pairs of prime numbers whose difference is 2.

Express the following as the sum of two odd primes:

(a) 44 (b) 36

(c) 24 (d) 18

Number of primes between 1 to 100 is _____.

2 is the only _____ number which is even.

Two numbers having only 1 as a common factor are called numbers.