To add -4 and 5, draw the starting number on a number line and count to the right when adding numbers. What is the difference in temperature between a desert at 40 °C and a mountain top at -2 °C? \(40 ...

Same signs give a positive: \(3 + (+2) = 3 + 2 = 5\) Same signs give a positive: \(3 - (-2) = 3 + 2 = 5\) Different signs give a negative: \(3 + (-2) = 3 - 2 = 1 ...

Young children can crudely add and subtract numbers before they have learned the rules of arithmetic, a new study finds. Researchers presented five- and six-year-old children with problems such as, ...