Primary 2 Maths | Subtraction with Borrowing Guide | Align, Borrow Ten, Check by Adding

2026-11-09

Tutor lesson-prep guides · Primary Maths

A child writes 265 for 523 minus 268, because 3 minus 8 was turned around into 8 minus 3. This lesson drills one sentence: if it will not subtract, borrow, and one borrowed unit is ten.

Objectives — Students can: (1) set a three-digit subtraction in columns with ones, tens and hundreds aligned; (2) borrow 1 from the next column when a column is too small, reducing the column borrowed from by 1; (3) check by adding the difference to the subtrahend to recover the starting number.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Subtraction within 20	What is 13 minus 8	5
Place value	Is the 5 in 523 in the hundreds or tens place	Hundreds
Addition with carrying	What is 268 plus 157	425

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-8 min	Diagnostic	Let them compute 523 minus 268 and collect the errors	Try it once
8-18 min	Alignment	Ones, tens, hundreds on three rows, subtrahend underneath	Rewrite the sum
18-32 min	Borrowing	Ones: 3 minus 8 needs 1 borrowed from the tens	Say each borrow aloud
32-44 min	Borrowing across zero	400 minus 157 borrows twice through the tens	Finish then compare
44-54 min	Checking	Difference plus subtrahend must give the start	Both checks once
54-60 min	Exit check	Three questions collected and marked	Work independently

03 Teaching script (read it out)

Scene 1: Align first, then decide whether to borrow

Subtraction in columns follows the same rule as addition: one place value per row, ones under ones, tens under tens, hundreds under hundreds, with ones at the right and the subtrahend below.
Misalignment guarantees a borrowing error, because borrowing from the next column means the column immediately to the left. After writing any vertical sum, have them tap right to left: ones, tens, hundreds.

Students do: write 523 minus 268 in columns and label each row ones, tens, hundreds.

Scene 2: Borrow 1 as 10, and reduce the column you borrowed from

Two steps: when the top digit is too small, borrow 1 from the column immediately to the left; that borrowed 1 is worth 10 where it lands. For 523 minus 268: ones, 3 minus 8 is too small, borrow from the tens, so the ones become 13 minus 8, which is 5. The tens lost 1, leaving 1, and 1 minus 6 is too small again, so borrow from the hundreds: 11 minus 6 is 5. The hundreds lost 1, leaving 4, and 4 minus 2 is 2. The difference is 255.
The step everyone drops is reducing the column borrowed from. So make the borrow visible: strike through the digit the moment it is borrowed, turning it into the new number.

Students say: why the tens column becomes 11 minus 6, and where that 1 came from.

Scene 3: Check: add the difference back to the subtrahend

There is one check: difference plus subtrahend equals the starting number. 255 plus 268 must give 523, and recovering the original number means the subtraction was right.
Add a sanity check as well: the difference is always smaller than the starting number. An answer larger than 523 is impossible. Near-equal numbers also give a small difference, so 523 minus 268 giving 255 is plausible while 365 is far too large.

Students do: check 400 minus 157 equals 243 by addition, and explain why the tens column borrowed twice.

04 Question types and worked steps

Type	Example	Steps	Answer
Basic borrowing	Three digits minus three digits, one borrow	Borrow 1 from the left when too small	Reduce the column borrowed from
Repeated borrowing	Both tens and hundreds borrow	Rewrite each digit as you borrow	Never skip the reduction
Borrowing across zero	400 minus 157 with a zero in the middle	Borrow into the zero, then pass it on	The hundreds drop to 3
Word problem	How many more one quantity than another	Write the sum, compute in columns, state units	Answer sentence needs units

Sanity check (teach this): Sanity check: the difference is smaller than the starting number; a borrowed column drops by 1; 523 minus 268 is 255, not 265; 400 minus 157 is 243, borrowing twice through the tens; 255 plus 268 returns 523.

05 Independent practice (3 questions)

Question	Answer	What to watch
Alignment	Complete three half-written column sums	Ones lined up
Borrowing	523 minus 268 showing each borrow	The borrowed column is reduced
Across zero	400 minus 157 and 502 minus 246	The zero in the tens is handled
Checking	Check two answers by addition	Check direction not reversed

06 Common mistakes and what to say

Mistake	Student writes	Say this
Turning the subtraction around	3 minus 8 done as 8 minus 3	The top digit is too small. Which column can you borrow from?
Forgetting to reduce	Still using 5 in the tens after borrowing	You borrowed 1 from the tens; is it still 5? Have you struck it through?
Borrowing from the wrong column	Taking from the hundreds but adding 10 to the ones	Borrowing means the column immediately to the left. Which one did you take from?
Word problem answer too big	A difference of 600	The start was only 523, so how can the difference be larger? Compute again.

07 Homework (paper, section and question numbers)

Primary maths chapter index — All chapters by level
Teaching guide index — Same structure, other subjects
Redo this chapter — Questions 1 to 4 again, striking each borrow and checking by addition

08 Exit check (last 5 minutes)

Question	Answer	Decision
523 minus 268	255	265 means a reversed subtraction, back to act two
What happens to the column you borrow from	It drops by 1	Unchanged means act two again
How to check	Add the difference to the subtrahend	Subtracting again means act three

09 Tutor FAQ

Can they use mental arithmetic?

Only once the written form is correct. Columns make borrowing visible; going mental too early hides the errors.

Why strike through the digit?

It moves working memory onto paper. Holding three digits and two borrows at once overloads a Primary 2 child, and the strike removes one thing to remember.

Does this work for four digits?

Identically, with one more row. Alignment and borrowing ten are the same method for larger numbers.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.