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 ...

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, ...

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