How to use Python to Check for Prime Numbers!

what's going on you guys welcome back to the channel and today's video is how to check if a specific number is a prime value inside of python [Music] okay so a prime number specifically is any number that is only divisible by itself and one no other values and so we're going to create a program to actually check for it so let's start by getting the number that we want to check and let's get it as an input from the user so that makes this function a little bit that this program a little bit quicker to use enter the number you want to check now we don't have to hard code the value that we're checking against we can just use that every time so what we're going to do what we need to do to make sure something is prime is check and see if any of the numbers below that value are able to uh be divisible by it so let's say for i in range and we're gonna use a for loop because what this is going to do is it's going to start at two basically because every number is divisible by one but we're gonna start at two and we're just going to go forward and say if if you're divisible by 2 all the way up to this number minus 1 then you're not prime but if you get through that whole list and we haven't finished yet then it it could be a prime value so what we'll do is we'll say for i in range and we'll start with two because we don't wanna start with one everything is divisible by one so um we'll do two and then we'll say all the way up to my number and the reason this isn't my number minus one is the way python for loops work is they do include the start value of your range but they don't include the end value so actually this is going to check if our number was 10 it's gonna check if you're divisible by two three four five six seven eight and nine but not ten that's just how for loops in python work and what do we actually want check we wanna check if my number divided by that value basically has no remainder right like it's it's hold the vision so there's no remainder and python has this really useful built-in module operator called the modulo operator which is uh basically just saying the remainder after division so if we're going to divide by i as we go through this for loop i is the variable that keeps updating so it's two it's three it's four it's five and if we divide my number by i and there's no remainder so that's that's what this modulo is getting is the remainder that means the remainder is equal to zero then that means our number is not prime this number is not prime and so we'll print that out on the screen so they know and then we'll also just exit so that's how you get it to leave the for loop right if you're in the for loop and you get certain conditions that you want to end the check because the thing is if you're checking 400 you don't need to get all the way up to 40 to know that it's not prime because as soon as you're at 2 you know it's not prime so then you get four and it's not prime 10 it's not prime so just exit the for loop as soon as something's divisible by it um and then what we'll print onto the screen is if so now we're thinking if you get all the way through the for loop and we haven't exited the code yet that means that the for loop finished and we can say this number is prime so this right here is all you need to do to check if it's prime so go ahead and run that and let's check one that we know is prime like uh 13. this number is prime sweet now let's check like i was saying let's go ahead and check 400 and this number is not prime okay and you can check that with as many as you want um i don't know all the prime numbers i guess 177s not one but try some high numbers look them up online and and see what primes there are out there and just make sure it's working but this is all you need so super quick super easy python concept super useful to know i hope you found that useful if you did please consider liking the video subscribe to the channel it helps me out a ton be sure to check out all the other great content over there let me know if you have any questions or want to see something in a future video in the comments below and as always good luck with your code and thanks for watching thanks bye