Identifying the missing factor

Leon is getting ready to host a party. Now, it’s time to set the table. There will be six guests, so he needs to prepare for seven. Six guests, plus Leon himself. He has bought one bag of … … 35 cupcakes.

He might as well hand them all out? How many cupcakes on each plate then? Seven plates. 35 cupcakes in the bag. 7 times something is 35.

So, we know one factor. It is known: 7 We know the product. It is also known: 35. But we still don’t know the other factor. It is unknown.

How can Leon figure out the unknown factor? Well, Leon recognises this calculation from the times table. He has practised it, and knows that seven times five equals 35. So he places five cupcakes on each plate, and it adds up perfectly. The bag is empty, and everyone has the same number of cupcakes.

The unknown factor is five. The next package contains … … 21 doughnuts. Are you going to hand them all out, Leon? Okay, there are still seven plates on the table. And now he has 21 doughnuts to hand out.

So, seven times an unknown factor equals 21. Leon once again thinks of the times table. He remembers that 7 times three is 21. He places three doughnuts on each plate. Leon knows the times table, and therefore he can quickly and automatically identify the unknown factor.

And now, I am going to identify the unknown factor … in this … box… of biscuits! Uhm, Leon … What? Can it wait? I’m identifying unknown factors… Can you yourself find the unknown factor if you get a few tasks for practice? Remember that the answer you’re looking for, that is the unknown factor, is found in the times table.

Grab a pen and paper. Write down the missing factors. When you are done you can start the film again. The correct answers will be shown, and you can compare with what you wrote. Pause now.

And here are the correct answers. Pause again, and compare. Let’s do this exercise a few more times, but with different tasks. Pause again. Here are the correct answers.

Pause and compare. And let’s do the drill one last time. Pause now. Here are the correct answers. If you quickly found the correct answers, that’s great!

It means you know the times table, and that it comes to you automatically. This is the exact purpose of all the exercises. Did you find it hard? Did you have to think for a long time to find the right answers? If so, the times table is not yet perfectly automatic for you.

But it will be soon, with just a little bit more practice. Let’s practise getting the party started. Welcome!