Question

Compute |1-3+5-7+...+13-15|

Answer 1

8

Explanation:

There are a couple different ways you can solve this, but this is generally the quickest way.

Identify a pattern in the problem. We can see that
`1-3=-2`,
`5-7=-2`, and so on. Subtracting every two odd numbers (without repeating any numbers) in that problem will always give us the same answer: -2.

So, we see how many pairs of odd numbers there are.

1 and 3, 5 and 7, 9 and 11, 13 and 15. We have four pairs of odd numbers. We can just multiply -2 by 4, which leaves us with an answer of -8.

Finally, since this is also an absolute value equation, the answer will be positive, so the final answer is 8.