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# What do divide a number by to see if its prime?

Updated: 9/18/2023

Wiki User

14y ago

2, 3, and every integer of the form 6n +/- 1 up to the square root of the number, rounded up. This is the simplest way to check a smaller subset of possible divisors, and yet not worry about the primality of the divisors.

Wiki User

14y ago

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Q: What do divide a number by to see if its prime?
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### How do you check if a large number is prime or a composite number?

You divide the number by 2. If the number is able to divide WITHOUT a remainder, then it is a prime number. If you divide a number by 1, you will get the same number. That is not a prime number.

### What prime number can divide 27 and 36?

The prime number 3 can divide 27 and 36.

### How do you find a fraction of a prime number?

Divide the prime number.

### Is 2011 prime?

Yes. To prove it, you can take the square root of 2011 (about 44.8), and divide 2011 by all the prime numbers under this number. You'll see none of them divide, so it's prime.

### What is the smallest prime number that will divide 147 evenly?

The smallest prime number that will divide 147 evenly is three.

### What are prime numbers between 80 and 90?

There are only 9 numbers between 80 and 90 - so lets look at them all Remember we only need to find 1 number that will divide the number except for 1 and itself for it to be NON-PRIME. 81 - 3 will of course divide this number - so not prime. 82 - 2 will of course divide this number - so not prime. 83 - PRIME!!! 84 - 3 will of course divide this number - so not prime. 85 - 5 will of course divide this number - so not prime. 86 - 2 will of course divide this number - so not prime. 87 - 3 will of course divide this number - so not prime. 88 - 2 will of course divide this number - so not prime. 89 - PRIME!!! So, the only numbers between 80 and 90 that are primes are 83 and 89!

### Why it is that number 2 is the smallest number in Prime?

It isn't 1 is. 1 is always the smallest. Can you divide 1 and get a whole number? No a prime number is something that you can divide into, yes you can divide it, making it a negative number, but not a whole number. * * * * * In fact, 1 is NOT a prime (nor a composite), so 2 IS the smallest prime.

### Is 120 a prime or not prime number?

120 is NOT a prime number because you can divide it by 10 and 5 and 2....

### Is 267 a prime number?

No it is not. A prime number will only divide (to give an integer as a result) by 1 and itself. 267 will also divide by 89 &amp; 3 so it is not prime.

### Can you divide a prime number?

A prime number can only be divided evenly by one or by itself.

### How do you perform prime factorization on a number?

I THINK... you see if it can be either multiplied or divided by any other number but 1, and if you can divide or multiply by any other number it is composite, if it cant be divided or multiplied, it is prime...

### What prime number will divide into 215?

The prime numbers are: 5 and 43