Addition — Tasmanian Year 4 Maths
Estimating sums by rounding and checking answers, then adding and subtracting four-digit numbers in columns with regrouping. Two subtopics and 40 questions with worked solutions, aligned to AC9M4N07 and AC9M4N06.
Addition in Tasmanian Year 4
This topic makes written addition reliable. Students first learn to estimate a sum by rounding, so they know roughly what answer to expect, and then add and subtract four-digit numbers in columns, regrouping and trading where needed and checking each result with the inverse operation.
The two subtopics are Estimate and Check Addition, and Add and Subtract Four-Digit Numbers. Addition is one of the 20 topics in Tasmanian Year 4 Maths and belongs to the Number strand. It comes under Australian Curriculum codes AC9M4N07 (estimating and rounding to check answers) and AC9M4N06 (efficient strategies for adding and subtracting). It leads into Subtraction and Addition and Subtraction Problems, and later to larger numbers and decimals.
Subtopics
Addition: common questions
How do you estimate a sum?
Round each number to the nearest 10 or 100, then add the rounded numbers. For \(287 + 412\), round to \(300 + 400 = 700\). The exact answer, \(699\), is close to the estimate, so it is reasonable.
How does column addition with regrouping work?
Line up the places and start with the ones. For \(2658 + 1475\): \(8 + 5 = 13\), so write \(3\) and carry \(1\) ten; \(5 + 7 + 1 = 13\) tens, so write \(3\) and carry \(1\) hundred; \(6 + 4 + 1 = 11\) hundreds, so write \(1\) and carry \(1\) thousand; then \(2 + 1 + 1 = 4\). The answer is \(4133\).
How do you check an addition or a subtraction?
Use the inverse operation. If \(2658 + 1475 = 4133\), then \(4133 - 1475\) should give back \(2658\). A quick estimate is a second check: about \(2700 + 1500 = 4200\) is close to \(4133\).
What mistakes do children make, and how can they practise at home?
Common slips are not lining up the places, forgetting a carried \(1\), and in subtraction taking the smaller digit from the larger one instead of trading. At home, estimate the total of two or three items before reaching the checkout, then compare it with the receipt.
Which curriculum codes cover Addition in Tasmanian Year 4?
Estimating and checking sums comes under Australian Curriculum v9 code AC9M4N07, about using rounding to test whether answers are reasonable. Adding and subtracting four-digit numbers comes under AC9M4N06, about efficient strategies for calculating.