Solve the Multiplication Problem: 40 × 2

Q: Why is 40 × 2 = 80 and not 42?

Multiplication means repeated addition! 40 × 2 means adding 40 two times: 40 + 40 = 80. If you got 42, you accidentally added instead of multiplied.

Q: How can I remember that positive × positive = positive?

Think of it as groups of something good! If you have 2 groups of 40 positive points, you get 80 positive points total. Positive × Positive always equals Positive.

Q: What's the fastest way to multiply by 2?

Just double the number! Multiplying by 2 means adding the number to itself. So 40 × 2 = 40 + 40 = 80.

Q: How do I check if my multiplication is correct?

Use division to check! If 40 × 2 = 80, then 80 ÷ 2 should equal 40. You can also use 80 ÷ 40 = 2 to verify.

Q: Why do we write +40 × +2 in the explanation?

The + signs show that both numbers are positive. In basic math, we usually don't write the + for positive numbers, but it helps explain why our answer is positive too!

Basic Multiplication with Positive Integers

Complete the following exercise:

$40\cdot2=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:05 Let's solve this together!

00:09 Remember, a positive number times another positive number is always positive.

00:16 And that's how we find the solution to our question.

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Complete the following exercise:

$40\cdot2=$

Step-by-step solution

Let's recall the law:

$(+x)\times(+x)=+x$

Therefore, the sign of the exercise result will be positive:

$+40\times+2=+80$

Final Answer

Key Points to Remember

Essential concepts to master this topic

Rule: Multiplying two positive numbers always gives a positive result
Technique: Calculate 40 × 2 = 80 using basic multiplication facts
Check: Verify by division: 80 ÷ 2 = 40 ✓

Common Mistakes

Avoid these frequent errors

Confusing multiplication with addition
Don't add 40 + 2 = 42 instead of multiplying! Addition combines quantities while multiplication means repeated addition or groups. Always use the × symbol to multiply: 40 × 2 means two groups of 40.

Practice Quiz

Test your knowledge with interactive questions

Convert $\frac{7}{2}$ into its reciprocal form:

FAQ

Everything you need to know about this question

Why is 40 × 2 = 80 and not 42?

Multiplication means repeated addition! 40 × 2 means adding 40 two times: 40 + 40 = 80. If you got 42, you accidentally added instead of multiplied.

How can I remember that positive × positive = positive?

Think of it as groups of something good! If you have 2 groups of 40 positive points, you get 80 positive points total. Positive × Positive always equals Positive.

What's the fastest way to multiply by 2?

Just double the number! Multiplying by 2 means adding the number to itself. So 40 × 2 = 40 + 40 = 80.

How do I check if my multiplication is correct?

Use division to check! If 40 × 2 = 80, then 80 ÷ 2 should equal 40. You can also use 80 ÷ 40 = 2 to verify.

Why do we write +40 × +2 in the explanation?

The + signs show that both numbers are positive. In basic math, we usually don't write the + for positive numbers, but it helps explain why our answer is positive too!

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