Column Subtraction with Exchanging!

Year 3: Subtracting a 2-Digit Number from a 3-Digit Number (With Regrouping)

Time to Exchange from the Tens!

Let's subtract! If the top ones digit is smaller than the bottom ones digit, you'll need to exchange one ten from the tens column. This makes the ones digit bigger by 10, and the tens digit smaller by 1. Then subtract the ones, then the tens, and finally the hundreds.

Practice Column Subtraction with Regrouping

Write your answers in the boxes. Remember to exchange if you need to!

Subtraction Power Move: Borrowing from the Tens with 3-Digits!

Hello Super Subtractors! You're doing amazingly well with column subtraction. Today, we're going to tackle a really important skill: subtracting a 2-digit number from a 3-digit number when we need to do some regrouping (or "borrowing" or "exchanging") from the tens place to the ones place. This happens when the ones digit on top is smaller than the ones digit you need to take away. Let's learn how to make that tens place help out the ones place!

Regrouping from Tens to Ones: The How-To Guide

Remember, the first step is always to line up your numbers perfectly by place value, with the bigger (3-digit) number on top.

Ones go under Ones.
Tens go under Tens.
The 2-digit number won't have a digit in the hundreds place.

Let's Subtract with Regrouping: Example 342 − 25

Here’s how we solve it:

Step 1: Write the numbers one above the other, aligned correctly.

  H T O  (H for Hundreds, T for Tens, O for Ones)
  3 4 2
−   2 5  (Align the 25 under the tens and ones of 342)
-------  (Draw a line underneath for your answer)

Step 2: Look at the Ones Column – Do we need to regroup? In the 'Ones' (O) column, we have 2 take away 5 (2 − 5). We can't take 5 away from 2 without going into tricky numbers! So, yes, we need to regroup from the tens place.

Step 3: Regroup (Borrow/Exchange) 1 Ten for 10 Ones.

Go to the 'Tens' (T) column of the top number (342). It has 4 tens.
We "borrow" 1 ten from these 4 tens. So, the 4 tens becomes 3 tens. Cross out the 4 and write a small 3 above it.
The 1 ten we borrowed is worth 10 ones. We add these 10 ones to the 2 ones we already had in the ones column. So, 2 + 10 = 12 ones. Cross out the 2 in the ones column and write a small 12 above it.

     ³ ¹²   <-- Shows the regrouping: 4 tens became 3 tens, 2 ones became 12 ones
  H T O
  3 4 2
−   2 5
-------

Step 4: Now Subtract the Ones Column. Look at our new 'Ones' (O) column. We now have 12 take away 5 (12 − 5). 12 − 5 = 7. Write the 7 under the ones column.

     ³ ¹²
  H T O
  3 4 2
−   2 5
-------
      7

Step 5: Subtract the Tens Column. Now look at our new 'Tens' (T) column. Remember we used one ten, so we have 3 tens take away 2 tens (3 − 2). 3 − 2 = 1. Write the 1 under the tens column.

     ³ ¹²
  H T O
  3 4 2
−   2 5
-------
    1 7

Step 6: Subtract (or Bring Down) the Hundreds Column. Finally, look at the 'Hundreds' (H) column. We have 3 hundreds in the top number. There's no hundreds digit in 25 to subtract (it's like a 0 there). So, 3 take away 0 (or just "bring down the 3") is 3. Write the 3 under the hundreds column.

     ³ ¹²
  H T O
  3 4 2
−   2 5
-------
  3 1 7

So, 342 − 25 = 317! You've expertly regrouped from the tens to the ones!

Practice Your Tens-to-Ones Regrouping! (18 Questions)

Ready to be a regrouping superstar? Here are 18 questions where you'll subtract a 2-digit number from a 3-digit number. You'll need to look carefully at the ones column and regroup from the tens when necessary. Line up your numbers, and take it one column at a time!

(Your web app with the 18 questions will go here. The app should ideally visually support the regrouping process.)

Why is This Regrouping Skill So Important?

Solves Many Subtraction Problems: This type of regrouping is very common in everyday subtraction.
Shows Deep Place Value Knowledge: You really understand how a ten can become ten ones.
Essential for Accuracy: Following the regrouping steps correctly helps you avoid mistakes with trickier sums.
Builds Maths Problem-Solving Skills: It teaches you how to adjust numbers to make subtraction possible.

Guidance for Grown-Ups: Supporting Tens-to-Ones Regrouping

When subtracting a 2-digit number from a 3-digit number that requires regrouping from tens to ones (e.g., 342 – 25), the key is understanding the exchange of 1 ten for 10 ones. Alignment also remains critical.

Revisit Base-Ten Blocks: Physically exchanging one ten rod for ten one cubes when the ones subtraction isn't possible is the clearest way to demonstrate this.
Consistent Notation for Regrouping: Ensure children consistently cross out the original tens digit, write the new (smaller) tens digit above, and cross out the original ones digit, writing the new (larger by 10) ones digit above.
"More on the Floor? Go Next Door!": This classic rhyme can help children remember when to regroup: if the bottom digit in the ones column ("the floor") is bigger than the top digit, they need to "go next door" to the tens place to get some more.
Check the Hundreds: Remind children that in these specific problems, the hundreds digit isn't directly involved in this regrouping step (though it would be if they were subtracting from the tens and the tens became zero, requiring borrowing from hundreds – that’s a next step!).