Using multiplication to work out the right number of slabs

Speaker 1: So today, Nyasha, what we need to do is complete the patio here.

Unfortunately we couldn't finish it yesterday because of the rain.

What I'd like you to do first of all is calculate how many slabs we need to complete the patio.

Speaker 2: OK, no problem.

Speaker 1: Brilliant, thank you very much.

Speaker 2: (TO AUDIENCE) The first thing I am going to do is count the number of slabs that are already laid around the perimeter.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

That will help me in working out the number of the slabs that I will need to cover the remainder of the area.

1, 2, 3, 4, 5. Now that I know there's 10 slabs by 5 slabs I can go and draw my sketch.

Speaker: So now I know how many slabs there are within the perimeter I'm going to use that to help me work out how many more slabs I need to fill out the area.

I will just do a sketch to help me work that out.

I'm going to use the squares to represent the slabs so I'm going to draw 10 squares going this way and then 5 coming down this way.

Also remembering there's 3 slabs still to be laid out.

So the slabs that I'm going to be shading in are the ones that have already been laid out.

I'm just going to join up from that end to that end.

This will then help me work out how many more slabs I need.

So there's 10 going that way, and 5 going that way, they're the ones that are already laid out.

This remaining area is how many more slabs I need to fill out which is obviously the 9 slabs across this way and the 4 which are coming across this way, plus the 3 that are up here.

So now I'm just going to count up the squares to tell me how many slabs I'm going to need altogether.

So it's 4, 8, 12, 16, 20, 24, 28, 32, 36 slabs plus the 3 that are up here.

That'll be 39 slabs altogether.

I've worked out that I need 39 slabs.

I'm just going to double-check that that's correct by doing 9 slabs times 4, that then gives me 36 plus the 3 slabs that are up here that gives me a total of 39 slabs.

Speaker 1: How's it going then, Nyasha?

Speaker 2: Yeah, not bad. I've basically used the slabs already laid as a guide to help me work out how many more slabs I needed to fill out the area.

So the area was 9 by 4, which is 36 as well as the 3 slabs there, which is 39 slabs altogether.

Speaker 1: That's brilliant. So you've basically worked out your perimeter and from that you've been able to work out your area.

Great stuff. So what we can do now is carry on laying the patio.

Speaker 2: Brilliant.

Speaker 1: Alright.