Adding and subtracting · Year 1

In Year 1 you learn: adding and subtracting within 10; adding and subtracting within 20; counting on and back on a number line.

Adding puts amounts together; subtracting takes away or finds the difference between two amounts. They are opposites: one undoes the other, so every subtraction can be checked with an addition. Good mental strategies (counting on, partitioning, using bonds) make both quick and reliable.

Key facts

• Adding can be done in any order: 7 + 5 = 5 + 7. Subtracting cannot.
• Find a difference by counting up from the smaller number.
• Check a subtraction by adding the answer back on.
• Look for pairs that make 10 or 100 when adding three numbers.

Worked examples

Other years

• Adding and subtracting · Year 2
• Adding and subtracting · Year 3
• Adding and subtracting · Year 4
• Adding and subtracting · Year 5