Four rules: Subtract from multiples of 10

Mental arithmetic is the core of successful number work and much can be done without resorting to written methods. Subtracting a 2 digit number from a multiple of 10 can be done ‘in your head’, but it does need care and using an efficient method.

Let’s look at:

50 – 27

Probably the easiest way to do this is by ‘counting on’.

Step 1:  Count on from 27 to the next whole ten (30), which is 3. Hold the three in your head for later.

Step 2: Count on in tens from 30 to 50, which is 20.

Step 3: Add the 20 to the 3 which is 23.

50 – 27 = 23.

(You will often find that children give the answer as 33 rather than 23. That is usually because they have counted on from 20 to 50 which is 30 and then added another 3 to get 33, ignoring the adjustment of the tens.)

Free maths worksheets below:

Subtract from multiples of 10 (p1 and p2)

The year 2011

A very happy new year to everyone. The new year will begin with a real mathematical twist as 2011 is a Prime Number. (Remember a prime number has just two multiples, itself and 1). Whilst there are an infinite number of prime numbers they are not easy to find. The last prime year was 2003 and the next will be 2017.

There is quite a lot of time in 2011, although the older you are the quicker it seems to pass by! The total time from 01-01-2011 to 01-012012 is 8,760 hours.
This is equivalent to 525,600 minutes.
You can also convert 365 days to 31,536,000 seconds.

We can also look forward to some spectacular dates this year such as 11th November 2011 which will be 11.11.11, but more of that as we go through the year. We can start with the first second of the first minute of the first hour of the first day of the first month of the new year, which will be:

1.1.1.1.1.11 (127 is 1111111 in binary)

As for the Chinese Calendar, 2011 will be the Year of the Rabbit: According to the Chinese this will be a placid year, very much welcomed and needed after the ferocious year of the Tiger.

Written method of addition

The Primary Framework for Mathematics uses a variety of methods to explain written addition in years 3 and 4, but by Year 5 it is expected that children know and understand how to use the standard method, which is exactly the same method that most parents learnt when they were at school.

The key to success is to line up the numbers to be added under each other so that the units line up, then the tens and then the hundreds. This will also apply when decimals are introduced. By keeping to 2 sets of 3-digit numbers this place value idea is re-inforced. It also really helps if children know, off by heart, all the answers to adding 2 single digits together – you would be surprised to know how many children are still using their fingers to add single digit numbers because they have never learnt them!

This is the second in our series of written addition pages. More worksheets can also be found in our Four Rules section.

3 digit addition (2)

Ten in the Bed by Penny Dale

Ten in the bedTen in the BedTen in the Bed by Penny Dale

Ten out of bedTen out of Bed by Penny Dale

Well, actually we have two great books to read to your children when they are snuggled up in bed ready to go to sleep. Most of us are aquainted with the nursery rhyme, There were ten in the bed and the little one said, “Roll over, roll over!”
They are about a young child (it could be a boy or a girl as s/he is only referred to as ‘The Little One’) who has ten cuddly animals in bed with him/her. They play games but one at a time the cuddly animals become sleepy and fall out of the bed (great for learning how to count down from 10) until the child is left all alone.
Now these toys are not all goody goodies and there is a lot of action going on in the background, allowing for new stories to be made up every evening. The endings of both books are, of course, happy ones with them all back in bed, fast asleep.

Year 1 Counting and Number

Children need as much practice as possible with counting up to 10 and you can not have too many resources to help with this. Of course, counting in the real world is the best place, whether it is in the kitchen counting spoons, or on the beach counting shells. However, it is also useful to have resources which can be printed or looked at on a compter. Why not use the free Mathblog resources to help?

Watch your child when they are counting objects and see if they are saying one number name for each object and that the last number they say is the number in the set. Look also for children who move the object they are counting, or mark it so that it is not counted twice. Don’t always ask children to count the whole set – just ask them to count 5 of them and see if they know when to stop.

We have a growing number of counting worksheets which help with these skills.

Go to the year 1 Counting and Number worksheets

Five Little Ducks by Ian Beck

Five Little DucksFive Little Ducks

Five Little Ducks is a story about… yes, you guessed it, five little ducks! They go out one day, waddling down to the pond to play.
But, as they swim and play on the pond, one of them wanders off and disappears, and then another, and another until there is just one little duck left. You are not really sure what has happened to each of the ducks, especially as there is a fox lurking in the background. However, there is a happy ending as Mama Duck finds her missing ducklings snuggled up in the garden shed.
Great story for counting up and down to five, with wonderful illustrations.
Ian Beck was an illustrator for over 20 years (including the artwork for Elton John’s Yellow Brick Road album) and turned to writing children’s stories for his own first child.

There are several other books with the same title, but this is definitely my favourite.

Reception maths games: counting and colouring

We have a good selection of simple maths games which your reception/year 1 children may like to play. Here is one example.

Help Ted colour his white balloons. Just by clicking in the balloons the colour will change.

One click will make a balloon go Red.

Two clicks will turn the balloon Blue.

Three clicks will change the colour to Gold.

Don’t forget to press Go when you think the colours are correct!

This is great practice at counting, why not have a go?

More games can be found in our Maths Games section.

[flash http://mathsblog.co.uk/wp-content/uploads/2008/02/colour8balloons1.swf]

Balloon bursting puzzle

Here we have a nice little puzzle for older children. The Maths Ratty is holding a huge bunch of balloons with numbers on. All you have to do is work out which balloon is left when the three problems have been answered.

Children need to know a little bit about multiples, square numbers and prime numbers to do this, so it is aimed at the older primary age range. Good for a wet  break time leading up to Christmas.

Balloon bursting

Four rules maths worksheets

Whilst most of our worksheets are found in the categories related to the National Primary Framework for Mathematics which teachers use to plan their lessons, (such as ‘Knowing Number facts’ and ‘Calculating’) we have also included a more old fashioned category called ‘Four Rules’.

This section covers both mental and written methods of addition, subtraction, multiplication and division and it is a section which is steadily increasing over the weeks. With over 100 worksheets already, it covers skills from Year 1 right up to Year 6; from adding a single digit up to long division and there are some very clear descriptions about how to tackle these tasks.

Go to our Four Rules category

Year 3 maths worksheet: Counting on patterns

counting-on-in-3s

Number squares can be a great way to show some of the fantastic and fascinating patterns that numbers can make. We are used to the 10 by 10 number square but, of course, they can be any size and the different sizes can create different patterns when counting on. For example, the first number square on this maths worksheet is a 6 by 6 square. When the multiples of 3 are coloured we get two vertical lines of colour. However, when using a 7 by 7 square, the pattern changes. Why is this?

This type of exercise can be used many times and soon children should be able to predict the kind of pattern that will be made, as well as having some practice with learning their tables!

Counting on in 3s patterns