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

## Is 13 a prime numbers?

The prime numbers from 1 to 100 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

## Is 31 prime or not?

31 (thirty-one) is the natural number following 30 and preceding 32. **It is a prime number**.

## What do you call this pair of numbers 13 and 31?

Ex 3.2, 3 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.

## Why 31 is not a prime number?

No, since **31 has only two factors, i.e. 1 and 31**.

## Is 13 a prime or composite?

**Yes, 13 is a prime number**. The number 13 is divisible only by 1 and the number itself. For a number to be classified as a prime number, it should have exactly two factors. Since 13 has exactly two factors, i.e. 1 and 13, it is a prime number.

## How do you figure out if a number is prime?

To prove whether a number is a prime number, **first try dividing it by 2, and see if you get a whole number**. If you do, it can’t be a prime number. If you don’t get a whole number, next try dividing it by prime numbers: 3, 5, 7, 11 (9 is divisible by 3) and so on, always dividing by a prime number (see table below).

## Is 31 a composite number Yes or no?

Solution 1: **The number 31 is prime** because its only factors are one and itself. Solution 2: Thirty-one is a prime number. This is because the number 31 has only two factors: 1 and 31.

## Is 31a prime or composite?

Number 31 is **prime** because it doesn’t have proper factors. In other words, the only factors of 31 are 1 and itself.

## What are the factors of 31?

As the number 31 is a prime number, it has only two factors, such as one and the number itself. Therefore, the factors of 31 are **1 and 31**.

## Are 13 and 15 twin primes?

First Few Pairs of Twin Primes

The first fifteen pairs of twin primes are as follows: (3, 5), (5, 7), **(11, 13)**, (17, 19), (29, 31), (41, 43), (59, 61), (71, 73), (101, 103), (107, 109), (137, 139), …

## Which are co-prime numbers?

**Any two successive numbers/ integers** are always co-prime: Take any consecutive numbers such as 2, 3, or 3, 4 or 5, 6, and so on; they have 1 as their HCF. The sum of any two co-prime numbers are always co-prime with their product: 2 and 3 are co-prime and have 5 as their sum (2+3) and 6 as the product (2×3).

## What is the meaning of twin prime?

Definition of twin primes

: **a pair of prime numbers (such as 3 and 5 or 11 and 13) differing by two**.

## Is 61 a prime number Yes or no?

**Yes, 61 is a prime number**.

## What is the only even prime number?

The unique even prime number **2**. All other primes are odd primes. Humorously, that means 2 is the “oddest” prime of all.

## Which one is not a prime number?

The answer to this lies in the definition of prime numbers itself. For a number to be called as a prime number, it must have only two positive factors. Now, for 1, the number of positive divisors or factors is only one i.e. 1 itself. So, **number one** is not a prime number.

### References:

- https://thirdspacelearning.com/blog/what-is-a-prime-number/
- https://en.wikipedia.org/wiki/31_(number)
- https://www.teachoo.com/7536/2318/Ex-3.2–3/category/Ex-3.2/
- https://www.cuemath.com/numbers/is-31-a-prime-number/
- https://www.cuemath.com/numbers/is-13-a-prime-number/
- https://www.factmonster.com/math-science/mathematics/prime-numbers-facts-examples-table-of-all-up-to-1000
- https://www.mathgoodies.com/lessons/vol3/prime_composite
- https://argoprep.com/blog/is-31-a-prime-number/
- https://byjus.com/maths/factors-of-31/
- https://byjus.com/maths/what-are-twin-primes/
- https://byjus.com/maths/co-prime-numbers/
- https://www.merriam-webster.com/dictionary/twin%20primes
- https://byjus.com/maths/is-61-a-prime-number/
- https://mathworld.wolfram.com/EvenPrime.html
- https://byjus.com/maths/is-1-a-prime-number/