A prime number is a number that have the right to only be divided by itself and also 1 there is no remainders. Below we define what precisely this means, offer you a list of the element numbers children need to understand at major school and administer you through some practice prime number questions and also examples.

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What is a element number?

A prime number is a number higher than 1 with only two components – themselves and 1.

A prime number cannot be separated by any other numbers there is no leaving a remainder.

An example of a prime number is 13. It can only be separated by 1 and 13. Dividing a element number by one more number results in numbers left over e.g. 13 ÷ 6 = 2 remainder 1.

15 is not an instance of a element number due to the fact that it can be split by 5 and 3 and by itself and also 1.

15 is an instance of a composite number due to the fact that it has an ext than two factors.

Prime number examples

How to work-related out if a number is a element number or not.

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What space the element numbers?

There space 8 element numbers under 20: 2, 3, 5, 7, 11, 13, 17 and 19.

The very first 10 element numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.

There room 25 element numbers between 1 and 100.

Prime numbers can proceed well past 100. For example, 21,577 is a element number.

List of prime numbers to 100

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.

Smallest element number

2 is the the smallest prime number. It additionally the only even prime number – every other even numbers deserve to be divided by themselves, 1 and 2 in ~ least, definition they will have at the very least 3 factors.

Largest element number

One that the most well known mathematicians of the timeless era, Euclid, recorded a proof the there is no biggest prime number. But many scientists and also mathematicians space still searching to discover it as component of the an excellent Internet Mersenne element Search.

Thelargest well-known prime number(as the November2020) is282,589,933− 1, a number which has actually 24,862,048 digits when written in base 10. Before then the largest well-known prime number was 277,232,917-1, having 23,249,425 digits.

By the moment you check out this it might be also larger, however you deserve to follow its development on Wikipedia.

Common FAQs around prime numbers


Is 1 a element number

1 is not a element number because it has only one factor, specific 1. Element numbers should have precisely two factors


Is 51 a element number?

51 is not a prime number since it deserve to be divided by 3 and 17, and also by itself and 1. In other words it has 4 factors.



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Prime number in major school

Prime numbers are not presented in the UK till Year 5.

According come the nationwide Curriculum, Year 5 children should be teach to

“know and use the vocabulary of element numbers, element factors and composite (non-prime) number to establish whether a number up to 100 is prime and recall element numbers approximately 19.”

In Year 6, children should be able to“identify usual factors, common multiples and also prime numbers”.

How space prime numbers provided in the actual world?

One that the most important uses because that prime number is in cyber security – making information shared end the net safer.

In order come encrypt (make secure) things choose credit map details, medical records, also some messaging services prefer WhatsApp, software designers make algorithms making use of prime numbers.

By multiplying 2 very huge prime numbers with each other (some service providers use element numbers that are thousands of digits long!), we create an even larger number whose original determinants (the 2 very large prime numbers) room only well-known to us. Us then use this also larger number to encrypt ours information.

If everyone else desires to uncover what information we are sending, they have to find out what ours original components were. With prime numbers as lengthy as the people we have actually used, it can take them years or even decades of consistent trial and also error before they find even one. This guarantee our information is kept safe.

Wondering around how to describe other vital maths vocabulary to her children? examine out our major Maths Dictionary, or shot these major maths terms:

Prime number questions

1) A square number and a element number have a full of 22. What space the two numbers?

A: 9 and also 13

2) Emma thinks of two prime numbers. She adds the two numbers together. Her answer is 36. Write all the possible pairs of prime numbers Emma might be reasoning of.

A: 3 and 33; 5 and also 31; 7 and 29; 13 and also 23; 17 and 19

3) circle the two prime numbers – 29, 59, 39, 69, 29

A: 29 and also 59

4) create the three prime numbers which main point to do 231.

A: 3 x 7 x 11

CHALLENGE QUESTION: Chen choose a element number. That multiplies the by 10 and also then ring it come the nearest hundred. His price is 400. Compose all the feasible prime number Chen might have chosen.

A: 37, 41 or 43.

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Prime number worksheets

Prime number videos

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