Method in multiplying madness?

Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

These printable resources may be useful: Methods in Multiplying Madness

                                                            Methods in Multiplying Madness Support.

If you had to work out $23 \times 21$ how would you do it?

What if you needed to work out $246 \times 34$?

Here are eight videos showing four different methods for working out the two multiplications. Can you make sense of them?

Grid Multiplication



$23 \times 21$



$246 \times 34$

Column Multiplication



$23 \times 21$



$246 \times 34$

Multiplying with Lines



$23 \times 21$



$246 \times 34$

Gelosia Multiplication



$23 \times 21$



$246 \times 34$

Once you have watched the videos, make up some multiplication calculations of your own and have a go at answering them using all four methods. Check that you get the same answer each time!

Here are some questions to consider:

Why does each method work?

What do the methods have in common?

What are the advantages and disadvantages to each method?

Extension challenge

Here is a video of another multiplication method, one where no writing down is needed along the way. Can you make sense of the video, and explain how this method works?