Problem:
What is the value of
1−(−2)−3−(−4)−5−(−6)?
Answer Choices:
A. −20
B. −3
C. 3
D. 5
E. 21
Solution:
We know that when we subtract negative numbers,
a−(−b)=a+b
The equation becomes
1+2−3+4−5+6=(D)5​
OR
Like Solution 1, we know that when we subtract a−(−b), that will equal a+b as the opposite/negative of a negative is a positive. Thus,
1−(−2)−3−(−4)−5−(−6)=1+2−3+4−5+6
We can group together a few terms to make our computation a bit simpler.
1+(2−3)+4+(−5+6)=1+(−1)+4+1= (D) 5​
The problems on this page are the property of the MAA's American Mathematics Competitions