Multiplying positive and negative numbers | Pre-Algebra | Khan Academy

TL;DR

When multiplying two numbers with different signs, the product will be negative. When multiplying two numbers with the same sign, the product will be positive. If both numbers are negative, the product will be positive.

Transcript

We know that if we were to multiply 2 times 3, that would give us positive 6. And since we're going to start thinking about negative numbers in this video, one way to think about it I had a positive number times another positive number, and that gave me a positive number. So if I have a positive times a positive, that will give me a positive number... Read More

Key Insights

• ✖️ Multiplying a positive by a positive gives a positive product.
• ❎ Multiplying a negative by a positive or vice versa gives a negative product.
• ✖️ Multiplying two negative numbers gives a positive product.
• 🪈 The order of multiplication does not affect the result.
• ✖️ Understanding the concept of repetitive addition can help visualize multiplication.
• 0️⃣ Zero multiplied by any number is always zero.
• 📏 The rules of multiplying positive and negative numbers can be applied to various numerical examples.

Questions & Answers

Q: What happens when you multiply a positive number by a positive number?

When you multiply two positive numbers, the product will also be positive. This can be understood by repeatedly adding the positive number to itself and getting a positive result.

Q: How does multiplying a negative number by a positive number work?

When a negative number is multiplied by a positive number, the product will be negative. This is because one of the two numbers being multiplied is negative, resulting in a negative product.

Q: Does the order of multiplication matter?

No, the order of multiplication does not affect the product. Whether you multiply a positive number by a negative number or a negative number by a positive number, the result will be the same - a negative product.

Q: What happens when both numbers being multiplied are negative?

When multiplying two negative numbers, the negatives will cancel out, and the product will be positive. This is a unique case where two negatives result in a positive.

Summary & Key Takeaways

• Multiplying a positive number by another positive number results in a positive product.

• Multiplying a negative number by a positive number or vice versa yields a negative product.

• When both numbers being multiplied are negative, the product will be positive.

• The rules of multiplying positive and negative numbers can be understood by considering the canceling out of negatives and repetitive addition.