Answer 1

A prime number is a number which is only divisible by one and number itself.
This knowledge will be enough for you to make a program for it. But coding is part where I want you to attempt first

Answer 2

Можно определить простое число или нет, следующим способом: от исходного числа получить квадратный корень, и если он целый, то число - составное. Если нет, начинаем перебирать числа от 2 до корня, округлённого вниз до ближайшего целого. Делим исходное число по очереди на все эти числа до округлённого корня. Если случится деление без остатка, то число - составное. Иначе- простое. (1 не считается простым числом). Для оптимизации, начиная с 3 можно перебирать варианты с шагом 2, т.к. чётные числа - составные.

Answer 3

I advise you creating a function finding all divisors of a number... That's all I can say. Like Arsenic said, a prime number can only be divided by 2 numbers (1 and itself).

Answer 4

(Similar question of this answer was deleted.)

prime number is a positive integer, which is only divisible by 1 and itself.

Exceptionally 1 is not a prime number.

Between 1 and 10:
2, 3, 5 and 7 are prime numbers.
(rest 1, 4, 6, 8 and 9 are not prime numbers)

Having knowledge in primes will give chances to represent numbers in factor-representation:
4: 2*2
6: 2*3
10: 2*5
62: 2*31
840: 2*2*2*3*5*7
3: 3
5: 5
23: 23

which can be used to simplify rationals:
4850 / 4030 = (2*5*5*97) / (2*5*13*31)

We can take the factor-representation of both operands and then we just remove the common factors 2 and 5 from factor-representations of both operands:
(5*97) / (13*31)

Then we calculate the factor-representations:
(5*97) / (13*31) = 485 / 403

And:
485 / 403
is the simpliest rational representation of:
4850 / 4030