## What you need to know

Things to remember:

• When counting forwards or backwards in 10s, 100s, 1000s, or 10000, this is the same as adding or subtracting this amount.

We get powers of 10 by starting with 1 and multiply by 10.

$$1\times10=10$$

$$10\times10=100$$

$$100\times10=1000$$

$$1000\times10=10000$$

So, our powers of 10 are: 1, 10, 100, 1000, 10000…

Let’s start by adding 10s to $2135$

2135

$2135+10=2145$

$2145+10=2155$

$2155+10=2165$

And we can create a sequence; 2135, 2145, 2155, 2165…

Looking at the sequence we can see that the next number will be 2175.

What is the next number in the sequence?

3400, 3500, 3600, 3700, …

First, we have to see how much our sequence is changing by. If we choose two numbers next to each other, we can see that we’re adding 100 each time.

3400

$3400+100=3500$

$3500+100=3600$

$3600+100=3700$

To find the next number in the sequence, we have to add 100 to the last number.

$3700+100=3800$

The next number in the sequence is 3800.

What is the next number in the sequence?

9780, 8780, 7780, 6780, …

First, we have to see how much our sequence is changing by. If we choose two numbers next to each other, we can see that we’re subtracting 1000 each time.

9780

$9780-1000=8780$

$8780-1000=7780$

$7780-1000=6780$

To find the next number we have to subtract 1000 from the last number.

$6780-1000=5780$

So, the next number in the sequence will be 5780.

## Example Questions

#### Question 1: What is the next number in the sequence?7430, 7420, 7410, 7400, …

First, we have to see how much our sequence is changing by. If we choose two numbers next to each other, we can see that we’re subtracting 10 each time.

7430

$7430 +10=7420$

$7420+10=7410$

$7410+10=7400$

To find the next number we have to subtract 10 from the last number.

$7400-10=7390$

So, the next number in the sequence will be 7390.

#### Question 2: What is the next number in the sequence?2500, 3500, 4500, 5500, …

First, we have to see how much our sequence is changing by. If we choose two numbers next to each other, we can see that we’re adding 1000 each time.

2500

$2500 +1000=3500$

$3500+1000=4500$

$4500 +1000=5500$

To find the next number we have to add 1000 to the last number.

$5500-1000=6500$

So, the next number in the sequence will be 6500.