HI

I'm developing a set o Scratch lessons showing 10 year old school children how to us Scratch to write simple mathematical programs. For example, a 7 times table program multiples 9x7 by adding 9 to itself 7 times - illustrating the principle that multiplication is repeated addition. The plan is to go on to show how you can do the same thing using the ‘repeat’ loop.

My problem is that I'm finding it very difficult to construct the expression 9+9+9+9+9+9+9 from pairs of 9+9 - as offered by Scratch. Can anyone suggest a reliable method for constructing my expression?

Roger D

I'm not quite sure what you are trying to do. You can make a variable add on to itself to show repeated addition.

If the number varies you need to use a loop as shown.

Hi

Thanks for responding, and obviously I didn't make myself sufficiently clear. To add 7 lots of 9 together, I wan to ‘assemble’ multiple copies of the addition operator block, which comes with just two parameter ‘holes’ - so 9+9 is easy. After a bit of experimentation, I've now worked out how to solve my problem. Basically, I add a second addition operator block to the right-hand parameter hole of the first block - creating a block with 3 holes. I then repeat this process - always adding the new block to the right-most hole - until I've got a block with 7 holes.

It's a bit clumsy, but it works!

best regards

Roger D

You could add 7 lots of 9 to a list then count through the list combining their values like this. Then you don't have to worry about all those join blocks. I added a wait 1 second so the kids can watch the numbers get added to the list and they can watch the answer count up.

https://scratch.mit.edu/projects/349705388/

If you still need help you might be best sharing what you have.