Calculate the Sum: Solving 8 + 9 + 2 Step by Step

Q: Why did we change the order from 8+9+2 to 8+2+9?

The commutative property tells us we can add numbers in any order! We rearranged to make $ 8+2=10 $ first because adding to 10 is much easier than adding to 17.

Q: Is it always better to make groups of 10?

Usually yes! Our number system is base-10, so making tens helps with mental math. Look for pairs like 1+9, 2+8, 3+7, 4+6, or 5+5 that equal 10.

Q: What if I get a different answer doing it left to right?

If you get a different answer, double-check your arithmetic! The order shouldn't change the sum. Try both ways: $ 8+9+2 $ and $ 8+2+9 $ should both equal 19.

Q: Can I use this strategy with bigger numbers?

Absolutely! For example, with 27+15+3, you could regroup as 27+3+15 to get 30+15=45. Look for numbers that make friendly sums like 10, 20, 50, or 100.

Basic Addition with Regrouping Strategy

Solve the following exercise:

$8+9+2=\text{ ?}$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 Let's arrange the exercise so it will be easy for us to solve

00:07 We'll solve according to the order of operations, from left to right

00:11 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 exercise:

$8+9+2=\text{ ?}$

Step-by-step solution

Since the exercise only involves addition, we will use the commutative property to solve it.

$8+2+9=$

Now let's solve the exercise from left to right:

$8+2=10$

$10+9=19$

Final Answer

Key Points to Remember

Essential concepts to master this topic

Commutative Property: Numbers can be added in any order without changing the sum
Technique: Regroup $8+2=10$ first to make mental math easier
Check: Count up from 8: 9, 10, 11...17, 18, 19 ✓

Common Mistakes

Avoid these frequent errors

Adding left to right without strategic regrouping
Don't just add $8+9=17$ then $17+2=19$ every time! While this works, it's harder mental math. Always look for pairs that make 10 first, like $8+2=10$ , then add the remaining number.

Practice Quiz

Test your knowledge with interactive questions

$74+32+6+4+4=\text{?}$

FAQ

Everything you need to know about this question

Why did we change the order from 8+9+2 to 8+2+9?

The commutative property tells us we can add numbers in any order! We rearranged to make $8+2=10$ first because adding to 10 is much easier than adding to 17.

Is it always better to make groups of 10?

Usually yes! Our number system is base-10, so making tens helps with mental math. Look for pairs like 1+9, 2+8, 3+7, 4+6, or 5+5 that equal 10.

What if I get a different answer doing it left to right?

If you get a different answer, double-check your arithmetic! The order shouldn't change the sum. Try both ways: $8+9+2$ and $8+2+9$ should both equal 19.

Can I use this strategy with bigger numbers?

Absolutely! For example, with 27+15+3, you could regroup as 27+3+15 to get 30+15=45. Look for numbers that make friendly sums like 10, 20, 50, or 100.

Do I have to show the regrouping step?

It depends on your teacher's requirements, but showing your thinking is usually good practice! Write $8+9+2 = 8+2+9 = 10+9 = 19$ to demonstrate your strategy.

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