Prime numbers list how to#

Once we have the table and the balls, we should place them on the table beginning with the first space, trying to form a rectangle. And we will get as many balls as the number we have chosen. To check if it is a prime number or not, we are going to use a table that is very similar to Montessori cards to multiply. Let’s pick a number at random, 16 for example. Pay close attention! We are going to give you a trick to know if a number is prime or not, without having to look for its divisors, but in a way that is more fun and gives us the divisors (if they have them).

Prime numbers list how to#

Now you can search for lots of prime numbers! How to Find Prime Numbers In short, a number is prime if it only has 2 divisors: 1 and itself.

Is 8? No! Because its divisors are 1, 2, 4, and 8.

Is 5? Yes! Because its divisors are 1 and 5.

Is 4? No! Because its divisors are 1, 2, and 4.

These are the types of numbers we call prime numbers.Īre there more prime numbers? Of course! Let’s look for some more:

So 7 can only be divided by 1 and 7, its only divisors are 1 and 7. Sara can share the pieces of candy between 7 people, giving them one piece each: Henry is so lucky! He got all of the pieces of candy!Īre there other ways to do it? We cannot divide 7 by 2, 3, 4, 5, or 6, …but 7 is possible! Now Sara has 7 pieces of candy and wants to share them, but doesn’t know how many people she can share them with so that everyone gets the same amount and none are leftover. We are going to try with another number, 7 for example. These numbers are known as the divisors of 6. In other words, we can divide the number 6 and get 0 as a remainder when we divide it by 1, 2, 3, and 6.

We have 6 pieces of candy that we can share (with an exact division) between 1, 2, 3, and 6 people. Since 6 divided by 6 is 1, we can give 6 children 1 piece of candy each. We do not have exact divisions with 4 and 5, but we do with 6. If we divide 6 pieces of candy between 3 people it is also an exact division and each person will get 2 pieces of candy: We are going to continue with the next number, 3. Since 6 divided by 2 is 3, each person gets 3 pieces of candy! The next possibility is to divide them between 2 people. This way that person will have 6 pieces of candy. The first and easiest way is to give them to one person, in other words, divide by 1. Sara has 6 pieces of candy that she wants to share, but she doesn’t know how many people she can share them with so that everyone gets the same amount and none are leftover. To help you better understand prime numbers, we are going to explain an exercise. We’re sorry that we can’t show all of them, as you know there is an infinite amount. Let’s take a look at the prime numbers from 100 to 1,000. Since Euclid, who was the first to show that there were an infinite amount in 4th century B.C, did not know the concept of infinity he said ”prime numbers are more than any fixed multitude of them” meaning if you imagine 100, there are more, and if you imagine one million there are still more. How many prime numbers are there in total? We have known since ancient times that there are an infinite amount, so it is impossible to list all of them. Notice that between 1 and 100 there are 25 prime numbers. It’s a process called the Sieve of Eratosthenes. The Greek mathematician Eratosthenes (3rd-century B.C) designed a quick way to find all the prime numbers up to any given number. You don’t have to memorize them but it would be best if you remember the smaller numbers, such as 2, 3, 5, 7, 11, 13. This is our list of prime numbers from 1 to 100. All of these numbers had already been crossed out so we have finished crossing out all of the composite numbers on our table. The next prime number is 11, so we cross out all of the multiples of 11 which are 22, 33, 44, 55, 66, 77, 88, and 99. Then we have the prime number 7 and we cross out all of the multiples of 7. The next prime number is 3, so we can cross out all the multiples of 3 since they will be composite numbers.Īfter 3, is the next prime number 5, so we cross out all of the multiples of 5. We cross out all of the multiples of 2 on the table. 2 is a prime number but all of the multiples of 2 will be composite numbers since they will be divisible by 2. We are going to create a table with all of the prime numbers that exist up to 100. So, if you divide the number by anything other than one or itself, you will get a remainder that is not zero. Prime numbers are the numbers that are only divisible by themselves and 1, in other words, if we try to divide them by another number, the result is not a whole number.