A GAA club orders 234 club badges, and each badge costs €3. Roughly how much will the whole order cost, before we work it out exactly?

Here is a question to get your thinking going: what is 200 × 3? What is 30 × 3? And what is 4 × 3? If we knew all three of those, would we have enough to answer the badge question?

The interactive draws each number as a rectangle, then splits it into boxes you can multiply one at a time. Watch how each box fills, and predict each answer before it appears. The box answers get added to give the whole thing.

The boxes are not drawn to size, so the interactive marks them 'not to scale'. That is fine: the hundreds box is really much bigger than the tens or units box, so we imagine it wider than it looks. Each box answer is called a partial product.

Now we work one product through together on the board: 243 × 4. Watch the three-digit number partition into hundreds, tens and units so the rectangle splits into three boxes, then predict each partial product before we fill it in. Put your hand up when you have an answer for a box. The boxes are not drawn to size, so remember the hundreds box is really the biggest. Once all three boxes are filled, we add the parts to find the whole answer.

Today we solve these GAA and club problems together: first 123 club badges at €3 each, then €215 raised on each of four days, then 308 steps walked each day for five days, then 246 cans collected by seven classes. Each one is a step harder, and the one to watch is 308 steps, because it has a zero in the tens place.