How_To_Be_Good_At_Math

72 NUMBERS •^ SCALING

Height

15 cm

12 treats are

made with 100 g

of chocolate and

80 g of puffed rice

Scaling down

A photograph, like this robot selfie, is a

perfect example of scaling down.

The robot is 75 cm tall in real life. In

the photo, he is 15 cm tall. So, he is

five times smaller in the photo.

In the photo, the robot looks the same,

but smaller. Every part of him has been

reduced in size by the same amount.

Scaling

Scaling is making something larger or smaller while

keeping everything in the same proportion – which means

making all the parts larger or smaller by the same amount.

Scaling up

Scaling up is making every part of a thing larger. We can scale up

amounts as well as objects and measurements.

We know that 12 is 2 times

6. So, if we multiply both
   ingredients by two, we can
   make twice as many treats.

On page 70, we saw a recipe for six

chocolate treats. To make 12, we’ll

need more ingredients. But how much

more of each?

So, to scale up a

recipe, we need to

multiply all the ingredients

by the same amount.

The robot’s body is 40 cm wide. In the

photo, it’s 8 cm wide, which is five

times smaller than in real life.

MAKES 6 CAKES

50 g

40 g × 2 = 80 g

We can use scaling to

change numbers, amounts,

or the sizes of objects

or shapes.

HEIGHT 75

cm

WIDTH 40 cm

Width

8 cm

50 g × 2 = 100 g

40 g

MAKES 12 CAKES

? g

? g

?

?

Chocolate

Multiply both

amounts by two

Puffed

rice

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