Column subtraction with regrouping
Subtract in columns, exchanging (borrowing) between columns.
Taught in Primary 3 in Nigeria (NERDC), Year 3 in United Kingdom (National Curriculum), Grade 4 in Canada (Ontario).
Nigeria (NERDC)
Primary 3
- Strand
- Basic Operations
- Called
- Column subtraction with regrouping
- How it's taught
- 'Borrowing' notation with crossed-out digits is standard; steps recited aloud.
United Kingdom (National Curriculum)
Year 3
- Strand
- Addition and Subtraction
- Called
- Column subtraction with regrouping
- How it's taught
- Taught as 'exchanging' with base-ten apparatus before the compact written method.
Canada (Ontario)
Grade 4
- Strand
- Number
- Called
- Column subtraction with regrouping
- How it's taught
- Student-invented and mental strategies first (decomposing, compensating, open number lines); standard algorithms are consolidated later than in other systems.