Addition and Subtraction

Addition and subtraction are the two operations you will use most frequently on the SET 11+ maths papers. Stage 1 requires speed and accuracy with multiple-choice questions, while Stage 2 demands clear written working. This lesson covers the essential methods and gives you strategies to avoid common errors.

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Column Addition

Column addition is the standard written method. Line up the digits by place value and add from right to left, carrying where necessary.

Worked Example

Calculate 4,687 + 2,759.

	Th	H	T	O
	4	6	8	7
+	2	7	5	9
	7	4	4	6

• Ones: 7 + 9 = 16. Write 6, carry 1.
• Tens: 8 + 5 + 1 = 14. Write 4, carry 1.
• Hundreds: 6 + 7 + 1 = 14. Write 4, carry 1.
• Thousands: 4 + 2 + 1 = 7.

Answer: 7,446

Top Tip: Always double-check your carrying. A single missed carry is the most common reason for losing marks on addition questions.

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Column Subtraction

Line up the digits by place value and subtract from right to left, exchanging (borrowing) where necessary.

Worked Example

Calculate 8,304 - 2,567.

Step 1: Start with the ones column: 4 - 7 cannot be done, so exchange 1 ten. The tens digit drops from 0 to... but the tens column is also 0, so you must exchange from the hundreds column first.

Step 2: The hundreds column has 3, which becomes 2 after lending 1 ten to the tens column. The tens column becomes 10, and then lends 1 ten to the ones column, becoming 9. The ones column becomes 14.

Step 3: Now subtract column by column.

• Ones: 14 - 7 = 7
• Tens: 9 - 6 = 3
• Hundreds: 2 - 5 — still cannot do this, so exchange from thousands: thousands goes from 8 to 7, hundreds becomes 12. 12 - 5 = 7
• Thousands: 7 - 2 = 5

Answer: 5,737

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Adding and Subtracting Decimals

The most important rule: line up the decimal points. Then add or subtract as normal.

Worked Example

Calculate 15.7 + 8.45.