Estimating money

Estimating money is a useful skill when you go shopping or you need to pay for something.

You can use estimation to quickly know if you have enough money to pay for the items.

When you estimate, you are not calculating with the exact amounts, instead you use rounding to make it easier to calculate in your head.

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It’s much easier to add pounds mentally than it is to add pounds and pence, so you often round to the nearest pound when you estimate money.

Let’s use rounding to estimate the total cost of these toys:

First, you need to round the amounts to the nearest pound. Then you will need to add them together to find the total.

You can use a number line to help or you.

The robot toy costs £2.99, so you label the number line with £2 and £3, because £2.99 is in between those amounts.

You can then plot halfway, because it helps when rounding.

Next, you plot the amount on and see whether it is closer to £2 or £3.

You can see that £2.99 is closer to £3 than £2, so you round the cost of the robot to £3.

You want to round it to the closer amount so you can be more accurate.

You do the same with the dinosaur toy. Label the number line with £4 and £5, because £4.20 is between these amounts.

Then label halfway between them, which is £4.50.

You can see that £4.20 is closer to £4 than £5.

So £4.20 rounded to the nearest pound is £4.

Now you add the estimated amounts to get your total estimate.

£3 + £4 = £7

The estimated cost of the robot and dinosaur toys is £7.

Estimating to the nearest 10p

If we want to have a more accurate estimation, you can round to the nearest 10p.

Let’s estimate the total cost of these two items.

Let’s use a number line to round the price of the birthday cake to the nearest 10p.

First, label it with £5.20 and £5.30, because £5.25 is in between these amounts.

You can also label halfway, which is £5.25.

When you plot £5.23 on the number line, you can see that it is closer to £5.20 than £5.30.

Therefore, the estimated cost of the birthday cake is £5.20.

Now you need to round the cost of the burger to the nearest 10p.

Label the number line with £4.50 and £4.60, because £4.58 is in between these amounts.

You can see that £4.58 is closer to £4.60.

Finally, add the amounts together to find the total estimate.

£5.20 + £4.60 = £9.80

The estimated cost of the birthday cake and the burger is £9.80.

Example 2