What is Subtracting Two-Digit Numbers With Borrowing?

S1-SA1-0070

Grade Level:

Class 2

Maths, Computing, AI

Definition

What is it?

Subtracting two-digit numbers with borrowing means taking a smaller two-digit number away from a larger two-digit number when the digit in the ones place of the top number is smaller than the digit in the ones place of the bottom number. To do this, we 'borrow' 1 ten from the tens place of the top number, converting it into 10 ones.

Simple Example

Quick Example

Imagine you have 35 rupees and you want to buy a packet of biscuits that costs 18 rupees. You can't directly take 8 rupees from 5 rupees. This is when you need to use borrowing to find out how much money you will have left.

Worked Example

Step-by-Step

Let's subtract 27 from 53.

Step 1: Write the numbers one below the other, aligning the ones and tens places.
53
- 27
----

Step 2: Start subtracting from the ones place. We need to subtract 7 from 3. Since 3 is smaller than 7, we cannot subtract directly.

Step 3: Borrow from the tens place. The 5 in the tens place becomes 4 (because we borrowed 1 ten). The 3 in the ones place becomes 13 (because 1 ten = 10 ones, and 10 + 3 = 13).
4 13
5 3
- 2 7
----

Step 4: Now subtract the ones: 13 - 7 = 6.
4 13
5 3
- 2 7
----
6

Step 5: Next, subtract the tens. Remember, the 5 became 4. So, 4 - 2 = 2.
4 13
5 3
- 2 7
----
2 6

Answer: So, 53 - 27 = 26.

Why It Matters

Understanding borrowing is fundamental for all arithmetic and is used in computing for basic operations. It's crucial for careers in finance, where you manage budgets, and in software development, where you write programs that perform calculations. Even AI models rely on such foundational math to process data!

Common Mistakes

MISTAKE: Not reducing the tens digit after borrowing. Students might borrow, make the ones digit larger, but forget to reduce the tens digit by 1. | CORRECTION: Always remember to decrease the tens digit by 1 after you borrow 1 ten from it.

MISTAKE: Subtracting the smaller digit from the larger digit without borrowing when the top digit is smaller. For example, in 53 - 27, some might do 7 - 3 = 4 in the ones place. | CORRECTION: If the top digit in a column is smaller than the bottom digit, you MUST borrow from the next place value to the left before subtracting.

MISTAKE: Borrowing from the tens place even when it's not needed. For example, in 48 - 23, some might borrow even though 8 is greater than 3. | CORRECTION: Only borrow when the top digit is smaller than the bottom digit in the same column.

Practice Questions

Try It Yourself

QUESTION: Your school library had 72 storybooks. Students borrowed 38 books. How many books are left? | ANSWER: 34 books

QUESTION: A farmer had 60 mangoes. He sold 29 mangoes at the market. How many mangoes does he have now? | ANSWER: 31 mangoes

QUESTION: Radha saved 91 rupees. She bought a pencil box for 45 rupees and then a packet of crayons for 28 rupees. How much money does Radha have left? (Hint: Subtract twice!) | ANSWER: 18 rupees

MCQ

Quick Quiz

What is 84 - 59?

The Correct Answer Is:

To solve 84 - 59, borrow 1 ten from 8, making it 7. The 4 becomes 14. 14 - 9 = 5 (ones place). Then, 7 - 5 = 2 (tens place). So, the answer is 25.

Real World Connection

In the Real World

Whenever you pay for groceries with cash and need change, or when a shopkeeper calculates how many items are left in stock after a sale, they are using subtraction, often with borrowing. Think about a kirana store owner calculating daily sales or a bank teller counting cash – these are real-world applications of this concept.

Key Vocabulary

Key Terms

BORROWING: Taking 1 from a higher place value and adding 10 to the current place value to allow subtraction | ONES PLACE: The rightmost digit in a whole number | TENS PLACE: The digit to the left of the ones place | SUBTRACTION: The process of taking one number or quantity away from another

What's Next

What to Learn Next

Great job mastering subtraction with borrowing! Next, you can learn 'Subtracting Three-Digit Numbers With Borrowing'. This will build on the same ideas but with larger numbers, preparing you for even more complex calculations!