What is column subtraction?
Column subtraction helps children subtract larger numbers by working one column at a time: units first, then tens, then hundreds. It turns a large calculation into small, visible steps.
The tricky part is borrowing. When the top digit is smaller than the bottom digit, one ten must be borrowed from the column on the left. That ten becomes 10 units in the current column.
The mechanism: subtract, borrow, continue
Children need three ideas: digits must be aligned, the calculation starts from the right, and borrowing changes two columns at the same time.
Align the columns
Units under units, tens under tens, hundreds under hundreds.
Check if subtraction is possible
If the top digit is large enough, subtract normally. If it is smaller, borrow.
Apply the borrowing
The column on the left loses 1 ten; the current column gains 10.
Worked example: 394 - 58
- Line up the numbers. In the units column, you need to calculate 4 - 8. Line up the numbers. In the units column, you need to calculate 4 - 8.
- 4 - 8 is not possible, so borrow 1 ten: 9 becomes 8 and 4 becomes 14.
- Units: 14 - 8 = 6.
- Tens: 8 - 5 = 3. Hundreds: 3 - 0 = 3.
- Result: 394 - 58 = 336.
Why does 4 become 14?
In 394 there are 9 tens and 4 units. To calculate 4 - 8, the units are not enough. One ten is changed into 10 units: 9 becomes 8 and 4 becomes 14.
This is the key idea behind borrowing: the value has not changed, only the way it is represented.
Tip: MateMatt shows each step visually, so children can focus on the method instead of guessing the next move.
Common mistakes in subtraction with borrowing
Most mistakes are not about basic subtraction. They happen because the child loses track of one part of the borrowing process.
Forgetting to reduce the ten
The child turns 4 into 14 but forgets that 9 must become 8.
Subtracting in the wrong direction
Some children solve 4 - 8 as 8 - 4. It feels easier, but it breaks the column method.
Misaligning the digits
If 58 is not aligned under tens and units, the child subtracts the wrong columns.
Losing track after borrowing
After the units are solved, the tens column is 8 - 5, not 9 - 5.
How MateMatt helps with borrowing
Borrowing is hard because two columns change at once. MateMatt makes those changes visible and separates them into small steps.
Shows the digit that changes
The borrowed ten is shown on screen, so the child sees 9 become 8.
Makes +10 visible
The units become 14 explicitly instead of staying as a hidden mental step.
Guides one column at a time
The app asks for borrowing first, then units, then tens.
Turns errors into correction
If the child makes a mistake, the feedback points back to the right step.
Practice exercises for column subtraction
Alternate exercises without borrowing and with borrowing, so the child learns when borrowing is actually needed.
No borrowing
74 - 32
Good for alignment and simple column subtraction.Borrowing in units
394 - 58
4 - 8 is not possible: one ten must be borrowed.Borrowing in tens
521 - 184
After the units, the tens column also needs attention.With zero
402 - 178
Useful once the basic borrowing mechanism is understood.Column subtraction FAQ
What does borrowing mean in subtraction?
It means taking one ten from the column on the left and turning it into 10 units in the current column.
Why do we start from the right?
Because borrowing in the units column can change the tens column.
How can I help a child who struggles with borrowing?
Show the exchange physically: one ten becomes 10 units. Then write both changes down.