Subtraction of 2 Digit Numbers

Week 2

Learning Outcome

Uses real-world situations and concrete objects to model and solve subtraction problems using abacus and place value models.

Objective

Children will be able to use an abacus and draw place value models to show and solve subtraction problems involving two-digit numbers, with and without regrouping.

Prerequisites

  • Children can perform single-digit subtraction.
  • The teacher can have a simple check for understanding at the beginning of the lesson by asking the children to show 2- digit subtraction using blocks.

Pre-teach Vocabulary

Children should be familiar with the terms such as, take away, less, before, remaining, subtrahend, and minuend.

Introduction: Subtraction on Abacus

  • The teacher could begin by reviewing subtraction using flashcards of subtraction.
  • For example, the teacher will ask the children to show the subtraction for the problem 23 – 14 =? using blocks on an A4 sheet and to show the answer.

The teacher will encourage the children to respond with more examples.

Materials required:

  • Abacus
  • Whiteboard and markers
  • Chart of place value (Tens and Ones)
  • Worksheets for practice
  • Coloured pencils
  • Math notebooks

Teaching Method: I Do – We Do – You Do

I DO (Teacher Modeling):

  1. Display the problem on the board.
  2. Using the abacus:
    • Place 5 beads in the tens column and 4 beads in the ones.
    • We are subtracting 23 from 54. So I will remove 2 beads from the tens      and 3 from the ones.
    • Count the remaining beads. 3 beads are left in the tens column and 1 bead in the ones column. So, the answer is 31.
  3. Drawing:
    • Provide children with a picture of a place value abacus (Tens and Ones).
      • In the Tens column, draw 5 beads.
      • In the Ones column, draw 4 beads.
    • Say, now we need to subtract 23 from 54. That is 2 tens and 3 ones.
      • Cross out 2 beads in the Tens column.
      • Cross out 3 beads in the Ones column.
    • Count the beads that are left:
      • 3 beads in the Tens column and 1 bead in the Ones column are left.
      • So, the answer is 31.

Drawing Beads on Abacus:

 Example Problem: 62 – 38 =?

  1. Draw 6 beads in the Tens column and 2 beads in the Ones column on a place value abacus template.
  2. Ask, can we subtract 8 beads from 2 in the Ones column? No. So, we need to regroup.
  3. Regrouping:
    • Trade 1 Ten bead for 10 Ones beads.
    • Cross out 1 bead from Tens and draw 10 beads in Ones. This is trading.
    • Now, there are 5 beads in the Tens column and 12 beads in the Ones column.
  4. Subtract:
    • Cross out 8 beads from the Ones column. 4 beads are left in the Ones column.
    • Cross out 3 beads from the Tens column. 2 beads are left in the Tens column.
  5. So, the final answer is 24.
  6. Talk through each step slowly. First we check the ones. Do we have enough to subtract? Yes. So we subtract and then look at the tens.
  7. If we do not have enough beads in the Ones column, we trade.

WE DO (Guided Practice):

Example Problem: 76 – 29 =?

  1. Ask the children to help you build the number 76 on the abacus: 7 tens and 6 ones.
  2. Ask, can we subtract 9 ones from 6 ones?
    • Children respond, “No.”
  3. Guide them to regroup:
    • Trade 1 ten (10 beads) for 10 ones. Now we have 6 tens and 16 ones.
    • Remove 9 ones from 16 ones. We are left with 7 ones.
    • Remove 2 tens from 6 tens. We are left with 4 tens.
    • So, the final answer is 47.
  4. Do the same problem using drawing.

Drawing Beads on Abacus:

Example Problem: 76 – 29

  1. Draw 7 beads in the Tens column and 6 beads in the Ones column on a place value abacus template.
  2. Ask, can we subtract 9 beads from 6 in the Ones column?” No. So, we need to regroup.
  3. Regrouping Step:
    • Trade 1 ten bead for 10 Ones beads.
    • Cross out 1 bead from the Tens column and draw 10 beads in the Ones column. This is trading.
    • Now, we have 6 beads in the Tens column and 16 beads in the Ones column.
  4. Subtract:
    • Cross out 9 beads from the Ones column. We are left with 7 ones.
    • Cross out 2 beads from the Tens column. We are left with 4 tens.
    • So, the final answer is 47
  5. Talk through each step slowly. First we check the ones column. Do we have enough to subtract? Yes. So we subtract and then look at the tens. If we do not have enough O news we trade.
  6. Ask children guiding questions such as, why did we regroup? What helped us find the answer?

YOU DO (Independent Practice):

  • Children are given subtraction problems like    
    1. 47 – 25 =?
    2. 61 – 34 =?
    3. 55 – 27 =?
  • Children will:
    1. Use their abacus to model and solve.
    2. Draw the problem using place value visuals in their notebooks.
    3. Write the final answer.

Video: Subtraction on Abacus – Coming soon

ISL Video: Subtraction on Abacus – Coming soon

LTM: DIY Flashcards – Coming soon

LTM: Printable Flashcards – Coming soon

Activity 1: Shopping with Subtraction

Objective: To apply subtraction of two-digit numbers in real-life situations by using play money to simulate shopping.

Importance of the activity for children:

Helps in developing:

  1. Gross motor skills (Walking)
  2. Fine motor skills (hand-eye coordination, writing)
  3. Cognitive skills (Counting, critical thinking, decision-making)
  4. Social skills (Cooperation, playing together, discussing)
  5. Language skills (Articulating)
  6. Emotional skills (Builds confidence in numeracy, promotes a sense of achievement that boosts self-esteem, and encourages pride in learning new skills)

Resources required:

  • Play money (bills and coins or printable sets)
  • Price tags or picture cards of classroom items (₹10 to 99 in value)
  • Shopping worksheets or recording sheets (With Abacus)
  • Pencil and eraser
  • (Optional) Cash register toy or pretend wallet

Setting for the activity:
The activity can be done indoors with a store area or shopping table set up.

Type of activity: Individual Activity (can also be done in pairs)

Preparation of activity:

  • Label classroom items or printed images with prices between ₹10 and ₹99
  • Prepare a set amount of play money for each Child (e.g., ₹50)
  • Create simple recording sheets with columns: Item | Price | Paid | Change
  • Role badges for ‘shopkeeper’ and ‘customer’ are optional.    

Role of the teacher: Demonstrator, observer, and facilitator.

Procedure:

  1. Introduction:
    • The teacher says, “Today you are going shopping! You’ll choose items and figure out how much change you get back using subtraction.”
  2. Activity Steps:
    • Each Child receives a set amount of play money (e.g., ₹50).
    • They select an item (e.g., a toy with a ₹28 price tag).
    • They subtract to find out how much change they should get (₹50 – ₹28 = ₹22).
    • They can use an abacus, base ten blocks, or drawings to help with subtraction.
    • They write the subtraction sentence and amount of change on their sheet.
    • Repeat for 2 or 3 items for each child.

Suggested Variations:

  • Give children a scenario. You bought a pencil for ₹36 and got ₹14 in change. How much did you pay? Children use addition and subtraction to solve the mystery (₹36 + ₹14 = ₹50). They explain their thinking either verbally or in writing.

Observations:

The teacher observes the children engaged in the activity to find:

  1. Can the children set up and solve a two-digit subtraction problem accurately?
  2. Do the children recognize when regrouping is needed?
  3. Is the child using an efficient strategy like mental math, drawing, and manipulatives?

Conclusion:
The children will be able to solve 2- digit subtraction problems using manipulatives.

Video: Shopping with subtraction – Coming soon

ISL Video: Shopping with subtraction – Coming soon

Activity 2: Roll and Subtract

Objective: 
To solve the subtraction by modelling numbers on the abacus using dice rolls and removing beads to find the answer.

Importance of the activity for children:

Helps in developing:

  1. Fine motor skills (Moving abacus beads)
  2. Cognitive skills (Understanding place value, visualizing subtraction)
  3. Social skills (Cooperation, taking turns with dice)
  4. Language skills (Articulating)
  5. Emotional skills (Builds confidence in numeracy, promotes a sense of achievement that boosts self-esteem, and encourages pride in learning new skills)

Resources required:

  • Two six-sided dice
  • A4 sheet for recording answers
  • Pencil and eraser
  • Crayons (optional for colour coding tens and ones beads)
  • Flashcards (with pre-written subtraction sentences, optional)
  • Abacus (physical or printed template)

Setting for the activity: 
The activity can be done indoors or outdoors, depending on the space availability.

Type of activity:
Individual activity (can be adapted for pairs or small groups)

Preparation of activity:
The teacher will ensure the availability of resources like dice, abacus (or templates), and worksheets. Flashcards with subtraction problems may be prepared in advance.

Role of the teacher: Demonstrator, observer, and facilitator.

Procedure:

  1. Each child gets:
    • Two dice to form a subtraction problem
    • An A4 sheet to record answers
    • An abacus or template for visualising numbers
  2. The teacher gives instructions:
    • The first number is modelled on the abacus using correct beads (tens and ones).
    • The second number tells how many beads to remove from the abacus.
    • Example: In 34 – 11
      • Represent 34 on the abacus: 3 beads in the tens place, 4 in the ones place.
      • Remove 1 ten bead and 1 one bead (for 11).
      • Count remaining beads: 2 tens and 3 ones. The answer is 23
  3. Children repeat the activity with new subtraction problems using dice.

Observation:
The teacher observes the children engaged in the activity to find:

  • Are the children able to model 2-digit numbers accurately using abacus beads?
  • If they are to subtract by removing the correct number of beads?

Conclusion:
The children are able to subtract 2- digit numbers with and without regrouping.

Video: Roll and subtract – Coming soon

ISL Video: Roll and subtract – Coming soon

Assessment

The teacher can give the practice worksheet to children, which can be followed by an assessment worksheet.

Practice Worksheet – Coming soon

Practice Worksheet (Enlarged) – Coming soon

Assessment Worksheet – Coming soon

Assessment Worksheet (Enlarged) – Coming soon

Cross-Curricular Connection:

  • Language Class:
    Children can recite number rhymes like ‘ten green bottles hanging on the wall’. Children can be instructed to create and solve small word problems involving subtraction and share them with others.
  • Art Class:
    Children can draw the answer to the math problem given. For example, the problem can be 20 -18 =? Children can draw two flowers or any two objects.
  • Physical Education Class:
    ‘Scoring and Subtracting’ (Mini Sports)
    Example: Basketball
    • Children take turns in throwing a ball.
    • They start with a score (e.g., 10 points) and subtract 1 point for every miss.
    • Total score = starting score – misses.

Check list for teacher:

ActivityYesNoSometimes
Children can:
Use abacus or draw abacus to do two – digit subtraction without regrouping
Use abacus or draw abacus to do two – digit subtraction with regrouping
Apply subtraction of two-digit numbers in real-life situations
Understand the word problems and solve them
Complete the activity in the given time
Do the activity independently
Express verbally and through actions, expressions or gestures
Enjoy teamwork, appreciate others, and are willing to learn from others

Home Activity

Assessment Worksheet – Coming soon

Assessment Worksheet (Enlarged) – Coming soon

Adaptations for addressing learner variability: Adaptations and strategies – Coming soon

Teacher Resource Document – Coming soon

Source and Attribution of images:
All images used in the above Assets and Aids are originally created.
This digital material has been developed by the Sri Sathya Sai Vidya Vahini Inclusive Education Project, a unit of Sri Sathya Sai Central Trust, Prasanthi Nilayam, as a collaborative offering in the service of our nation.