Solve the Expression: Finding the Missing Digit in 69+0?70-0

Q: Why doesn't adding zero change the number?

This is called the Identity Property! Zero is the additive identity, meaning any number plus zero equals that same number. It's like having 5 apples and adding 0 more apples - you still have 5!

Q: What about subtracting zero?

Subtracting zero also leaves the number unchanged. If you have 10 cookies and take away 0 cookies, you still have all 10 cookies. So $ 70 - 0 = 70 $.

Q: How do I remember which symbol means what?

Think of the symbols as hungry mouths! The open side always 'eats' the bigger number. So in 69

Q: Is 69 really less than 70?

Yes! You can count: 69, 70. Since 70 comes after 69 when counting up, 70 is bigger. On a number line, 70 is to the right of 69.

Q: What if both sides were equal?

If both sides gave the same result, we'd use the equals sign (=). But since $ 69 \neq 70 $, we need either depending on which is bigger.

Comparison Symbols with Identity Properties

$69+0?70-0$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Identify the correct mathematical sign

00:03 Any number plus 0 always equals the number itself

00:14 Any number minus 0 always equals the number itself

00:21 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$69+0?70-0$

Step-by-step solution

To solve this mathematical problem, we need to compare two expressions: $69 + 0$ and $70 - 0$ .

We'll follow these steps:

Calculate $69 + 0$ .
Calculate $70 - 0$ .
Compare the resulting values.

Let's break it down:

Step 1: Calculate $69 + 0$ .

We use the identity property: adding zero to a number does not change its value. Therefore, $69 + 0 = 69$ .

Step 2: Calculate $70 - 0$ .

Similarly, subtracting zero from a number does not change its value. Therefore, $70 - 0 = 70$ .

Step 3: Compare the two results.

We have $69$ from the first expression and $70$ from the second. Clearly, $69$ is less than $70$ .

Therefore, the answer is $69 + 0 < 70 - 0$ , represented as: $<$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Identity Properties: Adding or subtracting zero doesn't change values
Technique: Calculate each side: 69 + 0 = 69, 70 - 0 = 70
Check: Verify 69 < 70 by counting up from 69 to 70 ✓

Common Mistakes

Avoid these frequent errors

Assuming zero changes the result
Don't think 69 + 0 equals something different than 69 = wrong comparison! Zero has no effect on addition or subtraction. Always remember that adding or subtracting zero leaves the number unchanged.

Practice Quiz

Test your knowledge with interactive questions

$$ 20:1= $$

FAQ

Everything you need to know about this question

Why doesn't adding zero change the number?

This is called the Identity Property! Zero is the additive identity, meaning any number plus zero equals that same number. It's like having 5 apples and adding 0 more apples - you still have 5!

What about subtracting zero?

Subtracting zero also leaves the number unchanged. If you have 10 cookies and take away 0 cookies, you still have all 10 cookies. So $70 - 0 = 70$ .

How do I remember which symbol means what?

Think of the symbols as hungry mouths! The open side always 'eats' the bigger number. So in 69 < 70, the mouth opens toward 70 because it's larger.

Is 69 really less than 70?

Yes! You can count: 69, 70. Since 70 comes after 69 when counting up, 70 is bigger. On a number line, 70 is to the right of 69.

What if both sides were equal?

If both sides gave the same result, we'd use the equals sign (=). But since $69 \neq 70$ , we need either < or > depending on which is bigger.

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