Subtraction Borrowing Tricks That Make It Click

Why Borrowing Trips Kids Up

Kids learn the procedure:

Cross out the number
Make it one less
Put a 1 next to the other number

But they don't understand what they're doing or why.

Trick #1: The Trading Story

Tell this story:

"Each place value is like a box that can only hold digits 0-9. When we need more ones than we have, we go to the tens box and trade one ten for ten ones. It's like breaking a $10 bill into ten $1 bills. We have the same amount of money — just in smaller pieces."

Use it:

"We have 42. That's 4 tens and 2 ones. We need to subtract 7 ones, but we only have 2. Can we go to the tens box and trade? Now we have 3 tens and 12 ones. Still 42! Now we can subtract."

Trick #2: The Neighbor Check

Before subtracting each column, ask: "Do I have enough?"

Example: 53 - 28

Ones column: Do I have 8 ones to subtract? I only have 3. No. Need to borrow.

Tens column: Do I have 2 tens to subtract? I have 5 (well, 4 after borrowing). Yes. Just subtract.

Make it physical: Have them point to each column and ask out loud, "Do I have enough?" before calculating.

Trick #3: The "Bigger on Bottom" Alert

Teach them to scan the problem first:

"Look at each column. If the bottom number is bigger than the top, you'll need to borrow."

53 - 28: Ones column, 8 > 3. Alert! Borrowing needed.

This prevents the common mistake of subtracting smaller from larger (getting 35 instead of 25).

Trick #4: Cross Out and Add 10

The visual procedure:

Cross out the tens digit
Write one less above it
Write a small 1 in front of the ones digit (making it "10 + ones")

For 53 - 28:

Cross out the 5, write 4
The 3 becomes 13 (write a small 1 in front)
Now: 13 - 8 = 5, and 4 - 2 = 2
Answer: 25

Trick: Some kids do better writing the whole new number (13) rather than adding a small 1.

Trick #5: Subtract in Parts

Alternative strategy for kids who struggle with traditional borrowing:

53 - 28

Break 28 into 20 + 8:

53 - 20 = 33
33 - 8 = 25

Or break it differently:

53 - 28 = 53 - 30 + 2 = 23 + 2 = 25

This builds number sense and works for mental math.

Trick #6: Add to Check

After solving, add to verify:

53 - 28 = 25

Check: 25 + 28 = 53? ✓

This catches errors and reinforces the relationship between addition and subtraction.

The Hardest Part: Borrowing Across Zeros

400 - 156 is tricky because you can't borrow from 0.

The chain reaction method:

Start at ones: Need to borrow, but tens is 0.
Go to hundreds: Borrow 1 hundred → 10 tens.
Now borrow from tens: 10 tens → 9 tens and 10 ones.
Subtract: 10-6=4, 9-5=4, 3-1=2 → 244

Visual:

400 becomes 3 (hundreds), 10 (tens), 0 (ones)
Then 3 (hundreds), 9 (tens), 10 (ones)
Now subtract normally

Practice Makes Automatic

These tricks need practice to become natural:

Start with problems that need borrowing in only one place, then progress to harder ones.