Question

999-997+995-993 +..+ 103 - 101 = =

Answer 1

Ответ:

999-997+995-993+..+103-101=6

Answer 2

To find the sum of the numbers from 999 to 103 with a step of 2, you can use the formula for an arithmetic series:

Sum = (n/2) * [2a + (n-1)d]

Where:

• n is the number of terms
• a is the first term
• d is the common difference

In this case:

• a = 999
• d = -2 (because you're subtracting 2 each time)
• The last term, 103, is the 1st term + (n-1) * d, so 103 = 999 + (n-1) * (-2)

Now, you can solve for n in the last equation: 103 = 999 - 2(n-1)

Subtract 999 from both sides:

-896 = -2(n-1)

Divide both sides by -2:

448 = n - 1

Add 1 to both sides:

n = 449

Now that you know n, you can calculate the sum:

Sum = (449/2) * [2 * 999 + (449-1) * (-2)]

Sum = (449/2) * [1998 - 896]

Sum = (449/2) * 1102

Sum = 449 * 551

Sum = 244,999

So, the sum of the numbers from 999 to 103 with a step of 2 is 244,999.