The sum of the given sequence can be calculated by grouping the numbers in pairs:

(1-2) + (3+4) + (5-6) + (7+8) + (9-10) + (11+12) + ... + (97-98) + (99+100)

The sum of each pair can be simplified as follows:

-1 + 7 + -1 + 15 + -1 + 23 + ... + -1 + 199

Now, let's analyze the pattern of the sequence. The first number in each pair alternates between -1 and 1, while the second number increases by 6 each time. Therefore, we can rewrite the sequence as:

(-1 + 7 + -1 + 15 + -1 + 23 + ... + -1 + 199) = (-1 * 50) + (6 * (1 + 2 + 3 + ... + 50))

The sum of the numbers from 1 to 50 can be calculated using the formula for the sum of an arithmetic series:

1 + 2 + 3 + ... + 50 = (50 * (50 + 1)) / 2 = 25 * 51 = 1275

Substituting this value back into the equation:

(-1 * 50) + (6 * 1275) = -50 + 7650 = 7600

Therefore, the sum of the given sequence is 7600.