Multiply Three Numbers: 18 × 5 × 2 Step-by-Step

Q: Does it matter which numbers I multiply first?

No, it doesn't matter! Multiplication follows the associative property, so you can group the numbers any way you want. Try $ (18 \times 5) \times 2 $ or $ 18 \times (5 \times 2) $ - you'll get 180 both ways!

Q: Why did the solution multiply 5 × 2 first?

Smart strategy! Multiplying $ 5 \times 2 = 10 $ first creates a round number. Then $ 18 \times 10 = 180 $ is much easier to calculate mentally.

Q: How do I multiply by 10 quickly?

When multiplying any number by 10, simply add a zero to the end! So $ 18 \times 10 = 180 $. This works because 10 = 10¹.

Q: What if I get confused with the × symbol?

The multiplication symbol × means "groups of". So $ 18 \times 5 \times 2 $ means "18 groups of 5 groups of 2" or "18 groups of (5 groups of 2)". Both equal 180!

Q: Can I use a different order and still be correct?

Absolutely! You could calculate $ 18 \times 5 = 90 $ first, then $ 90 \times 2 = 180 $. All paths lead to the same answer when multiplying!

Multiplication Chain with Multiple Factors

Solve the following expression:

$18\times5\times2=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:02 We'll use the substitution method and solve this multiplication first, then continue

00:05 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

Solve the following expression:

$18\times5\times2=$

Step-by-step solution

According to the order of operations rules, since the exercise only involves multiplication, we can solve it from right to left:

$5\times2=10$

Now we will get the exercise:

$18\times10=$

Since this is a multiplication exercise with a round number ending in 0, we won't need to calculate at all, but simply add the 0 to the result we got before.

Therefore we will get the number:

$180$

Final Answer

$180$

Key Points to Remember

Essential concepts to master this topic

Order of Operations: Multiplication can be solved left to right or right to left
Technique: Group factors strategically: $5 \times 2 = 10$ , then $18 \times 10 = 180$
Check: Verify by calculating differently: $18 \times 5 = 90$ , then $90 \times 2 = 180$ ✓

Common Mistakes

Avoid these frequent errors

Adding instead of multiplying all factors
Don't calculate $18 + 5 + 2 = 25$ ! This mixes operations and gives a completely wrong result. Always multiply each factor: $18 \times 5 \times 2 = 180$ .

Practice Quiz

Test your knowledge with interactive questions

$$ 13+5+5= $$ ?

FAQ

Everything you need to know about this question

Does it matter which numbers I multiply first?

No, it doesn't matter! Multiplication follows the associative property, so you can group the numbers any way you want. Try $(18 \times 5) \times 2$ or $18 \times (5 \times 2)$ - you'll get 180 both ways!

Why did the solution multiply 5 × 2 first?

Smart strategy! Multiplying $5 \times 2 = 10$ first creates a round number. Then $18 \times 10 = 180$ is much easier to calculate mentally.

How do I multiply by 10 quickly?

When multiplying any number by 10, simply add a zero to the end! So $18 \times 10 = 180$ . This works because 10 = 10¹.

What if I get confused with the × symbol?

The multiplication symbol × means "groups of". So $18 \times 5 \times 2$ means "18 groups of 5 groups of 2" or "18 groups of (5 groups of 2)". Both equal 180!

Can I use a different order and still be correct?

Absolutely! You could calculate $18 \times 5 = 90$ first, then $90 \times 2 = 180$ . All paths lead to the same answer when multiplying!

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