Subtraction With Regrouping Basic 2 Mathematics Lesson Note

Learning Objectives

By the end of this week, pupils should be able to:

• Count and identify numbers from 1-510 (focus on 490-510)
• Write numbers 490-510 and 1-510 in numerals and words
• Identify place values of units, tens, and hundreds
• Perform subtraction with regrouping (borrowing)
• Solve real-life subtraction problems (shopping, change calculation)

Lesson Content

Day 1: Counting to 510

New Number Range:

• Practice counting from 1-510
• Focus on numbers 490-510: 490, 491, 492… 510
• Special attention to crossing 500: 499, 500, 501
• Learn to read: “five hundred and ten”

Number Writing Practice:

• Write 490, 495, 500, 505, 510 clearly
• Practice both numerals and words
• Emphasize the hundreds crossing

Day 2: Place Value Review

Understanding Place Value in 3-Digit Numbers:

• Hundreds (H), Tens (T), Units (U)
• Examples: 245 = 2H + 4T + 5U = 200 + 40 + 5

Place Value with Numbers to 510:

• 498 = 4 hundreds + 9 tens + 8 units
• 503 = 5 hundreds + 0 tens + 3 units
• 510 = 5 hundreds + 1 ten + 0 units

Day 3-4: Subtraction with Regrouping

What is Regrouping? When the bottom digit is bigger than the top digit, we need to “borrow” from the next column.

When Do We Regroup?

• When units digit on top is smaller than units digit below
• Example: In 52 – 27, we can’t do 2 – 7, so we borrow

Step-by-Step Method:

Example 1: 52 – 27

Step 1: Look at units    Step 2: Borrow from tens    Step 3: Subtract

   52                       4 12                        4 12

 – 27                     – 27                        – 27

 —-                     —-                        —-

Can’t do 2-7. Now we can do 12-7=5         25

Example 2: 63 – 48

  63    →    5 13    →    5 13

 – 48         –  48         –  48

 —-         —-         —-

              Can do       15

              13-8=5

              5-4=1

Day 5: Real-Life Applications

Shopping and Change: “Mom had 75 naira. She bought bread for 38 naira. How much change did she get?” 75 – 38 = 37 naira

Problem-Solving: Teaching students to identify when regrouping is needed and when it’s not.

Examples in Class

Place Value Examples:

• 456 = 4 hundreds + 5 tens + 6 units
• 507 = 5 hundreds + 0 tens + 7 units
• 490 = 4 hundreds + 9 tens + 0 units

Regrouping Examples:

Example 1: 74 – 26 (No regrouping needed)

   74

 – 26

 —-

   48

4 > 6? No, so 4 – 6 can’t be done simply. Actually, we need regrouping here too!

Let me correct this:

Example 1: 74 – 26 (Regrouping needed)

  6 14

    74

 – 26

 —-

   48

Example 2: 83 – 47

  7 13

    83

 – 47

 —-

   36

Real-Life Examples:

At the Market: “A shopkeeper had 92 oranges. He sold 57 oranges. How many oranges are left?” 92 – 57 = 35 oranges

Money Problems: “Dad had 84 naira. He spent 36 naira on fuel. How much money does he have left?” 84 – 36 = 48 naira

Exercises

Exercise 1: Number Practice

Write these numbers:

1. Four hundred and ninety-five = ___
2. Five hundred and eight = ___
3. 492 in words = ___
4. 506 in words = ___

Exercise 2: Place Value

Break down these numbers:

1. 478 = ___ hundreds + ___ tens + ___ units
2. 503 = ___ hundreds + ___ tens + ___ units
3. 495 = ___ hundreds + ___ tens + ___ units

Exercise 3: Identify Need for Regrouping

Look at these problems. Circle YES if regrouping is needed, NO if not:

1. 45 – 23 = YES / NO
2. 62 – 37 = YES / NO
3. 74 – 28 = YES / NO
4. 89 – 34 = YES / NO

Exercise 4: Subtraction with Regrouping

Solve these problems:

1. 52 2. 73 3. 64 4. 85

• 28 – 46 – 37 – 49

1. 91 6. 56 7. 82 8. 75

• 47 – 29 – 38 – 56

Exercise 5: Mixed Subtraction

Some need regrouping, some don’t:

1. 67 2. 54 3. 89 4. 76

• 23 – 28 – 45 – 34

Exercise 6: Real-Life Problems

1. A shop had 83 bottles of water. 47 bottles were sold. How many bottles are left? 
2. Mary had 92 stickers. She gave 56 stickers to her friends. How many stickers does she have now? 
3. A farmer had 75 chickens. 38 chickens were sold at the market. How many chickens remain? 
4. John saved 86 naira. He spent 49 naira on a toy. How much money does he have left? 

Exercise 7: Shopping Problems

1. Mom had 95 naira. She bought rice for 48 naira. How much change did she receive? 
2. Dad bought fuel for 67 naira from 100 naira. How much change should he get? 
3. A book costs 73 naira. If you pay with 100 naira, how much change will you receive? 

Fun Activities

• Borrow and Pay Back: Use play money to demonstrate regrouping
• Subtraction Detective: Find which problems need regrouping
• Market Day: Practice making change in role-play shopping
• Number Line Jumps: Use number lines to show subtraction

Homework

• Practice 8 regrouping subtraction problems daily
• Help parents calculate change when shopping
• Practice identifying when regrouping is needed
• Write numbers 490-510 neatly

Assessment

• Can the child count to 510 accurately?
• Do they understand when regrouping is needed?
• Can they perform subtraction with regrouping correctly?
• Can they apply subtraction to real-life situations?
• Do they understand place value concepts?

Teaching Tips

For Regrouping:

• Use physical objects (base-10 blocks) to show borrowing
• Emphasize “I can’t subtract, so I need to borrow”
• Practice identifying when regrouping is needed before solving
• Connect to real-life money situations for better understanding