Semi-formal addition
Semi-formal addition helps children practise adding three-digit numbers using a split-by-place-value method that bridges mental and written arithmetic. Read the short guide and look through the examples before choosing online practice or a printable worksheet.
How to solve this
- Semi-formal addition means writing the partial sums line by line: add hundreds, then tens, then ones, then combine.
- This method makes every carry visible and helps avoid errors when numbers are complex.
- Check by adding in the opposite direction (ones first, then tens, then hundreds) and confirming the same total.
Examples
347 + 286 (semi-formal)
633
428 + 159 (semi-formal)
587