You may use a calculator in this worksheet.

This worksheet is about Mathematical Matt, who says to his parents:

*"Let's change how much pocket money I get! *

*How about you give me 1p the first week, 2p the second week, 4p the third week, 8p in week 4, 16p in week 5 and so on...?"*

Here are the amounts in pence.

1 2 4 8 16 ...

Starting at 1, we get the next number by **multiplying by 2** or **doubling the previous number**.

These numbers are also called the **powers of 2**.

Week 1... 2^{0} = 1

Week 2... 2^{1} = 2

Week 3... 2^{2} = 4

Week 4... 2^{3} = 8

Week 5... 2^{4} = 16

The** 'powers of 2' **are an example of a **geometric **sequence, where each term after the first is found by multiplying the previous term by a fixed number, called the common ratio. The common ratio is 2.

The 'powers of 2' sequence goes on for ever. It is infinite and grows quickly!

**Example 1**

How much will Matt get, in pence, in **Week 7**?

**Answer**

He will get 2^{6} = **64p**.

**Example 2**

How much will Matt get, in pence, in total by **Week 4**?

**Answer**

He will get 1 + 2 + 4 + 8 =** 15p**.

**Example 3**

How much will Matt get, in pounds, in **Week 17**?

**Answer**

He will get 2^{16} =** **65 536p =** £655.36**.