A prime number is a number that can only be separated by itself and 1 there is no remainders. Right here we define what precisely this means, provide you a perform of the prime numbers kids need to know at main school and provide you through some practice prime number questions and also examples.

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What is a prime number?

A prime number is a number greater than 1 with only two determinants – themselves and also 1.

A element number can not be separated by any type of other numbers there is no leaving a remainder.

An example of a element number is 13. It can only be separated by 1 and 13. Splitting a element number by another number outcomes in number left over e.g. 13 ÷ 6 = 2 remainder 1.

15 is not an example of a prime number due to the fact that it deserve to be separated by 5 and 3 and by itself and 1.

15 is an instance of a composite number because it has an ext than two factors.

Prime number examples

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

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What are the prime numbers?

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

The an initial 10 prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.

There space 25 element numbers in between 1 and 100.

Prime number can continue well past 100. Because that example, 21,577 is a element number.

List of element 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 prime number

2 is the the smallest prime number. It also the only also prime number – every other also numbers can be separated by themselves, 1 and 2 in ~ least, an interpretation they will have at the very least 3 factors.

Largest element number

One of the most well known mathematicians of the classic era, Euclid, recorded a proof the there is no largest prime number. Yet many scientists and mathematicians are still browsing to find it as part of the great Internet Mersenne prime Search.

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

By the time you check out this it might be even larger, however you deserve to follow its progression on Wikipedia.

Common FAQs around prime numbers


Is 1 a prime number

1 is not a prime number due to the fact that it has actually only one factor, namely 1. Element numbers should have specifically two factors


Is 51 a element number?

51 is no a prime number due to the fact that it deserve to be split by 3 and also 17, as well as by itself and also 1. In other words it has four factors.



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Prime number in major school

Prime numbers space not introduced in the UK till Year 5.

According to the nationwide Curriculum, Year 5 kids should be teach to

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

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

How room prime numbers supplied in the real world?

One the the most vital uses for prime number is in cyber defense – making details shared end the web safer.

In order to encrypt (make secure) things prefer credit map details, clinical records, even some messaging services choose WhatsApp, software engineers make algorithms using prime numbers.

By multiplying two very big prime numbers with each other (some companies use prime numbers the are hundreds of digits long!), we develop an even larger number who original components (the two very large prime numbers) are only recognized to us. We then use this also larger number come encrypt ours information.

If anyone else desires to find what information we space sending, they have to discover out what ours original determinants were. V prime numbers as long as the persons we have actually used, it could take them year or even decades of continuous trial and error prior to they find even one. This ensures our details is maintained safe.

Wondering about how to define other vital maths vocabulary to your children? check out our primary Maths Dictionary, or shot these primary maths terms:

Prime number questions

1) A square number and also a prime number have actually a complete of 22. What are the two numbers?

A: 9 and also 13

2) Emma thinks of two prime numbers. She adds the 2 numbers together. Her answer is 36. Compose all the feasible pairs of prime numbers Emma could be reasoning of.

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

3) one the 2 prime numbers – 29, 59, 39, 69, 29

A: 29 and 59

4) compose the three prime number which main point to make 231.

A: 3 x 7 x 11

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

A: 37, 41 or 43.

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Prime number worksheets

Prime number videos

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