Solve the Multiplication Problem: 1×4×5 Step-by-Step

Q: Why do we multiply by 1 if it doesn't change anything?

Great observation! The number 1 is called the multiplicative identity because it doesn't change other numbers. In $ 1 \times 4 \times 5 $, the 1 is there to show all factors clearly.

Q: Can I multiply 4 × 5 first instead of 1 × 4?

Absolutely! The commutative property means you can multiply in any order. Whether you do $ 1 \times 4 \times 5 $ or $ 4 \times 5 \times 1 $, you'll get 20.

Q: How is this different from 1 + 4 + 5?

Big difference! $ 1 + 4 + 5 = 10 $ (addition), but $ 1 \times 4 \times 5 = 20 $ (multiplication). The × symbol means multiply, while + means add.

Q: What if there were more numbers to multiply?

Same process! For example, $ 1 \times 2 \times 3 \times 4 $ would be calculated step by step: 1×2=2, then 2×3=6, then 6×4=24.

Q: Why is the answer 20 and not 4 or 5?

Because we multiply all the numbers together! $ 1 \times 4 = 4 $, then $ 4 \times 5 = 20 $. Think of it as 4 groups of 5 objects each.

Multiplication Properties with Identity Element

$1\times4\times5=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:04 1 multiplied by any number always equals the number itself

00:12 Let's calculate the multiplications

00:20 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$1\times4\times5=$

Step-by-step solution

To solve this problem, we will use the properties of multiplication.

Step 1: Recognize that multiplying by 1 leaves the number unchanged. Hence, $1 \times 4$ simplifies directly to 4.
Step 2: Multiply the result from Step 1 by the remaining number. Thus, $4 \times 5 = 20$ .

After completing the steps, we observe that the final result of the calculation is $20$ .

Therefore, the solution to the problem is $\mathbf{20}$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Identity Property: Multiplying any number by 1 leaves it unchanged
Sequential Method: First calculate $1 \times 4 = 4$ , then $4 \times 5 = 20$
Check: Count by fives four times: 5, 10, 15, 20 ✓

Common Mistakes

Avoid these frequent errors

Adding instead of multiplying all factors
Don't calculate 1 + 4 + 5 = 10! Addition gives a completely different result from multiplication. Always use the × symbol to multiply: 1 × 4 × 5 means 1 times 4 times 5.

Practice Quiz

Test your knowledge with interactive questions

$1\times1000=$

FAQ

Everything you need to know about this question

Why do we multiply by 1 if it doesn't change anything?

Great observation! The number 1 is called the multiplicative identity because it doesn't change other numbers. In $1 \times 4 \times 5$ , the 1 is there to show all factors clearly.

Can I multiply 4 × 5 first instead of 1 × 4?

Absolutely! The commutative property means you can multiply in any order. Whether you do $1 \times 4 \times 5$ or $4 \times 5 \times 1$ , you'll get 20.

How is this different from 1 + 4 + 5?

Big difference! $1 + 4 + 5 = 10$ (addition), but $1 \times 4 \times 5 = 20$ (multiplication). The × symbol means multiply, while + means add.

What if there were more numbers to multiply?

Same process! For example, $1 \times 2 \times 3 \times 4$ would be calculated step by step: 1×2=2, then 2×3=6, then 6×4=24.

Why is the answer 20 and not 4 or 5?

Because we multiply all the numbers together! $1 \times 4 = 4$ , then $4 \times 5 = 20$ . Think of it as 4 groups of 5 objects each.

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