Video narration
What rules still work when you use fractions? Sharing a snack in equal portions gives you fractions. A rational number is a ratio of integers with a nonzero denominator. Its decimal ends or repeats. Add, subtract, or multiply rational numbers, and you get another rational number. Divide by one too, if the divisor isn't zero. Here's the key: fractions aren't exceptions to arithmetic. Addition and multiplication can switch order-that's commutative-and regroup-that's associative. Two plus three equals three plus two. Multiplication distributes over addition: multiply each part of a sum, then add. Zero changes nothing when added; multiplying by one changes nothing. Only a nonzero rational number has a reciprocal. But subtraction and division don't share those order-and-grouping rules. Three minus one isn't one minus three; dividing by zero is forbidden. So, yes: familiar rules apply, but subtraction and division don't commute, and zero can't be a divisor.