Evaluate these expressions (you may think of them as Starting Floor + Movement by referring to the Building of Fun). a. (+1) + (+4) = _____ b. (+4) + (+1) = _____ c. (+4) + (−3) = _____ d. (−1) + (+2) = _____ e. (−1) + (+1) = _____ f. 0 + (+2) = _____ g. 0 + (−2) = _____
+5
+5
+1
+1
0
+2
−2
Explanation
(a) Starting at Floor +1 and going up 4 floors reaches Floor +5. (b) Starting at Floor +4 and going up 1 floor reaches Floor +5. (c) Starting at Floor +4 and going down 3 floors reaches Floor +1. (d) Starting at Floor −1 and going up 2 floors reaches Floor +1. (e) Starting at Floor −1 and going up 1 floor reaches Floor 0 (ground floor). (f) Starting at Floor 0 and going up 2 floors reaches Floor +2. (g) Starting at Floor 0 and going down 2 floors reaches Floor −2.