Question

Вычислить сумму всех четных натуральных чисел меньше данного n . задача по информатике

Answer 1

СLS
INPUT n
FOR i = 1 TO n
IF INT(i/2) = i/2 THEN s=s+i
NEXT i
PRINT "сумма равна"; s
END

Answer 2

Calculating the Sum of All Even Natural Numbers Less Than a Given n

To calculate the sum of all even natural numbers less than a given number n, you can use the formula for the sum of an arithmetic series. The formula is:

Sum = (n/2) * (first term + last term)

In this case, the first term is 2 (the smallest even natural number) and the last term is n-2 (the largest even natural number less than n). Therefore, the formula becomes:

Sum = (n/2) * (2 + n-2) = (n/2) * n = n^2/2

So, the sum of all even natural numbers less than a given n is n^2/2.

Please note that this formula assumes that n is a positive even number. If n is an odd number, you can use the formula for the sum of an arithmetic series with a common difference of 2.

I hope this helps! Let me know if you have any further questions.

Example Code in Python

Here's an example code snippet in Python that calculates the sum of all even natural numbers less than a given n:

n = int(input("Enter a positive even number: "))
sum = (n**2) // 2
print("The sum of all even natural numbers less than", n, "is", sum)

In this code, we take the input from the user as the variable n, calculate the sum using the formula (n^2/2), and then print the result.

Please let me know if you need any further assistance!