Question

Aman is adding -11 + 10. He wants to write -11 as the sum of two numbers so that one of the numbers, when added to 10, will equal 0. How should Aman write -11 to complete this problem? a) -11 + 11 b) -5 + (-6) c) -10 + (-1) d) 0 + (-11)

Answer 1

Answer: Choice C. -10 + (-1)

Reason

Let's replace -11 in the original expression with -10+(-1).

-11 + 10

-10+(-1) +10

(-10+10) + (-1)

0 + (-1)

-1

The -10 and +10 pair up to cancel out. They are opposites of each other. The -10 can be thought of as going down 10 floors on a building. Then +10 is going up 10 floors. When combined, the two cancel out and you end up back on the same floor you started from.

This ultimately means -11 + 10 = -1

If you are at basement level 11, and go up 10 floors, then you'll arrive at basement level 1. Check out the diagram below to see the vertical number line diagram.