GRADE 2 · ALBERTAOUTCOME AB-MAT2-N2
L5 · Subtracting two-digit numbers
Learning goal
“I can subtract two-digit numbers by taking the tens first and then the ones, and by counting on along a number line when the numbers are close or cross a ten.”
Difference — the answer to a subtraction. In 87 - 24 = 63, the difference is 63.
Count on — to start at the smaller number and jump up to the bigger number. The jumps together make the difference.
Count back — to start at the bigger number and jump back by the smaller number.
Number line — a line of numbers in order. Jumps on the line show adding and subtracting.
Worked example
Subtract 87 - 24. Step 1 - SPLIT THE 24: 24 is 20 and 4. Step 2 - TAKE THE TENS: 87 - 20 = 67. Step 3 - TAKE THE ONES: 67 - 4 = 63. So 87 - 24 = 63. Big bites first, small bites last.
Check yourself — explain it
Why do we split 24 into 20 and 4 in 87 - 24?
Paired problem — example still visible
76 - 35: take 30, then 5. -> 76 - 30 = 46, then 46 - 5 = 41
Faded completion — last step is yours
68 - 23: 68 - 20 = 48, then 48 - ___ = ___ -> 3; 45
Ready to practise?
10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.