What is Checking an Answer? | Simple Explanation for Class 5-10

S0-SA1-1510

What is Checking an Answer (Skill)?

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Checking an answer is the skill of reviewing your solution to a problem to make sure it is correct and makes sense. It helps you catch mistakes before you submit your work or use the answer in real life. It's like double-checking your bag before leaving home.

Simple Example

Quick Example

Imagine you bought 3 packets of biscuits, and each packet costs ₹10. You calculated the total as ₹40. Checking your answer means quickly thinking: '3 packets at ₹10 each should be 3 x 10 = ₹30.' You immediately see your mistake and correct it to ₹30.

Worked Example

Step-by-Step

PROBLEM: Your school library has 125 storybooks. They just bought 78 new books. How many books are there in total now? You calculated the answer as 193.

STEP 1: Understand the original problem. We need to add the old books and the new books.
---STEP 2: Review your calculation. You did 125 + 78 = 193. Is this right?
---STEP 3: Try a different way to check. You can estimate! 125 is close to 100, and 78 is close to 80. So, 100 + 80 = 180. Your answer 193 is close to 180, so it seems reasonable.
---STEP 4: You can also subtract to check addition. If 125 + 78 = 193, then 193 - 78 should be 125. Let's do it: 193 - 78 = 115. Oh! This is not 125. There's a mistake!
---STEP 5: Re-do the original addition carefully: 125 + 78 = 203.
---STEP 6: Now, let's check the new answer. 203 - 78 = 125. Yes, this is correct!
ANSWER: There are 203 books in total.

Why It Matters

Checking your answers helps you build confidence in your problem-solving skills and avoid silly mistakes. This skill is crucial for engineers designing bridges, doctors prescribing medicines, or even a shopkeeper calculating change for a customer, ensuring accuracy in important tasks.

Common Mistakes

MISTAKE: Not checking at all or just glancing over the answer quickly. | CORRECTION: Take a moment to actively review your steps and consider if the answer makes sense in the context of the problem.

MISTAKE: Only re-doing the calculation the exact same way. | CORRECTION: Try to use a different method to check, like estimating, working backward, or using inverse operations (e.g., checking addition with subtraction).

MISTAKE: Assuming a 'big' number is always correct for addition or a 'small' number for subtraction. | CORRECTION: Always compare your answer to the original numbers and the operation. For addition, the answer should be larger than the individual numbers; for subtraction, it should be smaller than the first number.

Practice Questions

Try It Yourself

QUESTION: You bought a t-shirt for ₹350 and a cap for ₹120. You calculated the total as ₹480. Check your answer. | ANSWER: 350 + 120 = 470. So, ₹480 is incorrect. The correct total is ₹470.

QUESTION: A train journey from Delhi to Mumbai is 1400 km. After travelling 850 km, how much distance is left? You got 650 km. Check your answer using addition. | ANSWER: If 1400 - 850 = 650, then 650 + 850 should be 1400. 650 + 850 = 1500. So, 650 km is incorrect. The correct answer is 1400 - 850 = 550 km.

QUESTION: Your mobile phone plan gives you 2 GB of data per day. If you used 0.75 GB in the morning and 0.5 GB in the afternoon, how much data is left for the evening? You calculated 1.25 GB. Check your answer. | ANSWER: Total data used = 0.75 + 0.5 = 1.25 GB. Data left = 2 - 1.25 = 0.75 GB. Your answer of 1.25 GB was the data used, not the data left. The correct answer is 0.75 GB.

MCQ

Quick Quiz

Why is it important to check your answer after solving a math problem?

It helps you finish your homework faster.

It ensures your answer is correct and makes sense.

It makes the problem harder to solve.

It is only for very difficult problems.

The Correct Answer Is:

Checking your answer is important to ensure accuracy and confirm that your solution is logical. It doesn't necessarily make homework faster or problems harder, and it's useful for all types of problems, not just difficult ones.

Real World Connection

In the Real World

When you are buying groceries at a local kirana store and the shopkeeper tells you the total bill, you quickly check the calculation in your mind to make sure it's correct. Or, when you are tracking your monthly mobile data usage, you check if the data remaining matches what you expect, just like how ISRO scientists double-check every calculation before a rocket launch.

Key Vocabulary

Key Terms

REVIEW: To look over something again carefully. | ESTIMATE: To guess an approximate value or quantity. | ACCURACY: The quality or state of being correct or precise. | INVERSE OPERATIONS: Operations that undo each other (e.g., addition and subtraction).

What's Next

What to Learn Next

Now that you understand checking answers, you can explore 'Estimation and Rounding'. This skill helps you quickly approximate answers, which is a powerful way to check if your final calculated answer is in the right ballpark. Keep practicing!