Long Multiplication:
A tool to model what's happening; using partial product/distributive law to build understanding.
Age: 8+
Learning Objectives:
Year 5: to multiply numbers up to 4 digits by a one- or two-digit number using a formal written method, including long multiplication for two-digit numbers.
Year 6: to multiply multi-digit numbers up to 4 digits by a two-digit whole number using the formal written method of long multiplication.
Instructions:
- Choose between 2,3 and 4 digit numbers for the multiplicand using the light blue square grids, (top left).
- All of the multipliers are 2 digit numbers.
- Use the tick / check box to choose your chosen method: partial product or formal written method. (This won't change the calculation so you can do it both ways.)
- Notice where the colours match between the written method and the area model.
- Calculate each line/cell revealing the answers as you go.
- Clicking on the model reveals each partial product.
- "Carrying" is not automatic. The products will be correct but the user must drag on the carrying numbers where needed.
- The product at the end can be revealed one digit at a time.
- The area model is designed to be similar to one we might draw on paper. It is not to scale. I have tried to keep some sense of scale for understanding.
Have fun!