What is a Change Word Problem?

S1-SA1-0752

Grade Level:

Class 3

Maths, NLP, AI, Finance

Definition

What is it?

A Change Word Problem is a type of maths problem where something increases or decreases over time. You need to figure out how much something changed, how much there was to begin with, or how much there is now.

Simple Example

Quick Example

Imagine you have 5 delicious ladoos. Your friend gives you 3 more ladoos. How many ladoos do you have in total now? This is a change problem because the number of ladoos changed (increased).

Worked Example

Step-by-Step

PROBLEM: Riya had 12 colourful kites. She lost 5 kites while playing at the park. How many kites does Riya have left?
---STEP 1: Understand the starting amount. Riya began with 12 kites.
---STEP 2: Identify the change. She lost 5 kites, which means the number decreased.
---STEP 3: Decide the operation. Since the number decreased, we will subtract.
---STEP 4: Perform the calculation. 12 - 5 = 7.
---ANSWER: Riya has 7 kites left.

Why It Matters

Understanding change problems helps you think logically and solve everyday challenges. It's useful in careers like finance, where you track money changes, or even in AI, where computers learn from data that changes over time.

Common Mistakes

MISTAKE: Adding instead of subtracting when something is 'lost' or 'taken away'. | CORRECTION: Look for keywords like 'lost', 'spent', 'gave away', 'decreased' – these usually mean you need to subtract.

MISTAKE: Not identifying the starting amount correctly. | CORRECTION: Always read the problem carefully to find the initial number or quantity before any change happens.

MISTAKE: Mixing up the order of numbers in subtraction. | CORRECTION: In subtraction, the larger number (the starting amount) usually comes first. You can't take more than you have!

Practice Questions

Try It Yourself

QUESTION: A bus had 25 passengers. At the next stop, 8 passengers got off. How many passengers are left on the bus? | ANSWER: 17 passengers

QUESTION: Your mobile phone had 500 MB of data. You used 230 MB to watch a video. How much data is remaining? | ANSWER: 270 MB

QUESTION: A chaiwala made 35 cups of chai in the morning. In the afternoon, he made 20 more cups. If 10 cups were sold in total, how many cups of chai are left? | ANSWER: 45 cups

MCQ

Quick Quiz

Which of these is a Change Word Problem?

How many wheels do 3 auto-rickshaws have?

If a cricket team scored 150 runs and then scored 75 more runs, what is their total score?

What is the sum of 10 and 5?

How many days are there in 2 weeks?

The Correct Answer Is:

Option B describes a situation where the score changes (increases) from 150 to a new total. The other options are simple multiplication or addition problems without a 'change' over time.

Real World Connection

In the Real World

Change word problems are everywhere! When you check your bank balance on a UPI app, you're seeing how your money changes after you spend or receive some. Or, when a shopkeeper checks their stock, they calculate how many items they had, how many they sold, and how many are left.

Key Vocabulary

Key Terms

INCREASE: To become larger in amount or number | DECREASE: To become smaller in amount or number | STARTING AMOUNT: The initial quantity before any change | REMAINING: What is left after some part is taken away

What's Next

What to Learn Next

Next, you can learn about 'Compare Word Problems'. These problems ask you to find the difference between two quantities, which builds on your understanding of 'change' but in a different way. Keep up the great work!