Solve : 1000-999+998-997+... +4-3+2-1

divide it up into pairs.

each pair adds up to 1.
There are 500 pairs, so the sum is 500.

the answer is 500,500

Evaluate 1000- 999 + 998 -997 + ... + 4 - 3 + 2 - 1

500

To solve the given expression:

Step 1: Add the first two numbers, 1000 and -999: 1000 + (-999) = 1

Step 2: Add the next two numbers, 998 and -997: 998 + (-997) = 1

Step 3: Continue this pattern of adding the next two numbers and obtaining a result of 1.

Step 4: Since there are 500 pairs of numbers from 1000 to 1, we can conclude that the sum of all the pairs is 500*1 = 500.

Therefore, the solution to the expression 1000-999+998-997+... +4-3+2-1 is 500.