All concepts combined

This page mixes all four parts of the Primary 3 addition and subtraction chapter: column addition, column subtraction with renaming, mental addition and subtraction, and word problems. A question does not announce its method, so your child first decides whether to add or subtract, and whether to work in columns or in their head.

• Add numbers up to 4 digits in columns, renaming in any place where a column makes 10 or more.
• Subtract numbers up to 4 digits in columns, renaming across zeros where needed.
• Add and subtract two 2-digit numbers mentally by splitting, or by using a nearby tens number and adjusting.
• Decide whether a word problem needs a total, a difference or a missing part, and work backwards when the starting amount is unknown.
• Choose between a written and a mental method, and check an answer with the inverse operation.

A column sum must be larger than every number added, and a difference must be smaller than the larger of the two numbers. For the shuttlecocks or any other 'at first' story, run the changes forwards from your child's answer and see that it ends on the number left.

This set mixes the chapter's question types, from column addition and subtraction through zeros to mental methods and word problems. The Basic questions check each skill on its own, and the Intermediate questions ask for regrouping or two steps. The Challenge questions combine these, so your child must read each question to choose between adding, subtracting or a mental shortcut. When a question in this mixed set stalls, watch its own solution film and come back to it later from Revision.

What does P3 addition and subtraction within 10 000 cover? The MOE Primary 3 syllabus lists two outcomes: addition and subtraction algorithms with numbers up to 4 digits, and mental addition and subtraction of two 2-digit numbers. This chapter covers both and applies them to word problems.

How do I know when my child is ready for mixed practice? When the worked examples on each subtopic page make sense to your child and they can explain the steps aloud. The mixed set then trains choosing between adding and subtracting, and between a mental and a written method.

Should my child use a calculator for P3 addition and subtraction? These pages practise written and mental methods, so the working should be done without one. A calculator is useful afterwards for checking a long column sum.