Multiply & Divide Rational Numbers

How the lesson starts: Multiply & Divide Rational Numbers

Wally dives deep
Hi there! Wally the whale loves to dive. Every minute, he swims 6 meters deeper. Going down is negative, so each minute is −6. After 4 minutes, where is Wally? Let's learn to multiply and divide with negatives!
Four dives of −6
Multiplying is repeated adding. Wally starts at 0. Minute 1: down to −6. Minute 2: −12. Minute 3: −18. Minute 4: −24. So (−6) × 4 = −24. Every jump goes down, so a negative times a positive is negative.
Dividing two negatives
Wally dove −42 meters in all, going −6 each minute. How many minutes? That's (−42) ÷ (−6). It asks: how many jumps of −6 make −42? Count them: 7. Minutes are a positive count, so the answer is 7. Same signs give a positive answer.