What is 10-8+6-4+...+(-18)?  Choose the most appropriate option:  A) -8  B) 10  C) 12  D) -4  E) 16
The expression considers all even numbers between 10 and -18 with alternate addition and subtraction of the numbers.   The numbers to be used are: 10, 8, 6, 4, 2, 0, -2, -4, -6, -8, -10, -12, -14, -16, and -18.   Now, the first term is positive and the next term is subtracted. So, the required expression becomes,   10 - 8 + 6 - 4 + 2 - 0 + (-2) - (-4) + (-6) - (-8) + (-10) - (-12) + (-14) - (-16) + (-18)   = 10 - 8 + 6 - 4 + 2 - 0 - 2 + 4 - 6 + 8 - 10 + 12 - 14 + 16 - 18   = 58 - 62   = -4   Hence the correct answer choice is -4.
<result>D</result>
What is 10-8+6-4+...+(-18)?