Inaugurated by IN-SPACe
ISRO Registered Space Tutor
S1-SA1-1212
What is 100 - 25?
Grade Level:
Class 3
Maths, Computing, AI, Finance
Definition
What is it?
100 - 25 is a subtraction problem where we find the difference between the number 100 and the number 25. Subtraction means taking away one number from another to see what is left.
Simple Example
Quick Example
Imagine you have 100 rupees in your piggy bank. You buy a new cricket ball for 25 rupees. To find out how much money you have left, you would do 100 - 25.
Worked Example
Step-by-Step
Let's subtract 25 from 100 step-by-step:
1. Write the numbers one below the other, aligning the ones place and tens place:
100
- 25
-----
2. Start subtracting from the rightmost column (ones place). We have 0 - 5. Since 0 is smaller than 5, we need to borrow from the tens place.
3. Look at the tens place. It's also 0, so we borrow from the hundreds place (1).
4. The 1 in the hundreds place becomes 0. The 0 in the tens place becomes 10. Now, we borrow 1 from this 10 for the ones place.
5. The 10 in the tens place becomes 9. The 0 in the ones place becomes 10.
6. Now subtract the ones column: 10 - 5 = 5.
7. Subtract the tens column: 9 - 2 = 7.
8. Subtract the hundreds column: 0 - 0 = 0.
So, 100 - 25 = 75.
Why It Matters
Understanding subtraction is crucial for daily life and many advanced fields. It helps in managing your pocket money, calculating discounts while shopping, and even in complex areas like computer programming or financial planning for businesses.
Common Mistakes
MISTAKE: Subtracting smaller digit from larger digit without borrowing (e.g., 0 - 5 = 5) | CORRECTION: Always borrow from the next place value if the top digit is smaller than the bottom digit.
MISTAKE: Forgetting to reduce the number from which you borrowed (e.g., borrowing from 10 and still using 10 instead of 9) | CORRECTION: After borrowing, remember to subtract 1 from the digit you borrowed from.
MISTAKE: Misaligning digits, especially when one number has fewer digits than the other | CORRECTION: Always align the numbers by their ones place, then tens, hundreds, and so on, from right to left.
Practice Questions
Try It Yourself
QUESTION: What is 50 - 15? | ANSWER: 35
QUESTION: A bus has 75 seats. If 38 passengers are already seated, how many seats are empty? | ANSWER: 37
QUESTION: You have 200 ml of juice. Your friend drinks 50 ml, and then you drink 25 ml. How much juice is left? | ANSWER: 125 ml
MCQ
Quick Quiz
What is the result of 100 minus 25?
65
75
85
125
The Correct Answer Is:
B
The correct answer is 75. When you subtract 25 from 100, you are taking away 25 units, leaving 75 units remaining. Options A, C, and D are incorrect calculations.
Real World Connection
In the Real World
Imagine you're checking your mobile data usage. If you started the month with 100 GB and have already used 25 GB, you'd calculate 100 - 25 to know you have 75 GB left. This helps you plan your internet use for the rest of the month.
Key Vocabulary
Key Terms
SUBTRACTION: The process of taking one number or quantity away from another | DIFFERENCE: The result of subtracting one number from another | BORROWING: A method used in subtraction when a digit in the minuend is smaller than the corresponding digit in the subtrahend | PLACE VALUE: The value of each digit in a number based on its position (ones, tens, hundreds etc.)
What's Next
What to Learn Next
Now that you've mastered basic subtraction, you can move on to larger number subtractions and subtraction with decimals. These skills will help you solve more complex problems in daily life and higher maths.
