Resource of the Week: multiplying 2-digit numbers by 9 mentally.

multiply-by-9-mentally-1

A great deal is made of written methods of multiplication but it all depends on having good mental arithmetic skills.In fact much that might be done on paper can actually be done ‘in your head’.

A good example of this is that you can multiply most 2-digit numbers by 9 in your head. The most efficient way to do this is to multiply the number by ten and then subtract the number. For example:

46 x 9

First of all multiply 46 by 10 which is 460.

Then subtract 46 from 460 which is 414.

This maths worksheet shows how to do this and then gives some practice questions – but, a word of warning, you do have to be pretty good at subtraction to use this method.

Thgis, and much more can be found in the Four Rules category.

Multiply by 9 mentally (1)

Year 3 mental arithmetic: Sets 7 and 8

I continue with two more sets of mental arithmetic questions for Year 3. Today the questions are about notation of money, recalling addition and subtraction facts, tables and doubling and halving.

At the moment I am only publishing two sets of questions a week, but these can be used effectively to make up your own questions which can be read out. Mental arithmetic is one of the most important aspects of maths in the primary school and should not be neglected.

All these pages can be found in the Year 3 maths worksheets section under Mental Arithmetic.

Year 3 Mental Arithmetic (sets 7 and 8)

Year 1 maths resources

All the maths worksheets for Year 1 are to be found by clicking on the Free Maths Worksheets link at the top of the page. The worksheets have been organised into categories following the guidelines of the primary Framework for Mathematics, although this is now under review.

The categories are:

Counting and Number: looking at counting small numbers in steps of one and writing numbers.

Know number facts: counting on and back in twos and knowing addition facts to 5.

Calculating: including adding small numbers, taking away and an introduction to money

Understanding shape:  at this stage recognising triangles, rectangles and squares as well as introducing some 3D shapes

Measuring: using non standard measures and comparing

Handling Data: mainly making lists

Using and Applying Maths: making number stories and investigating.

Whilst there is a considerable amount here it is next to nothing compared to the URBrainy site which is the best that I have found online, with over 1700 colourful pages of maths for Year 1, including full answers.

Go to our Year 1 maths resources

Year 6 Equivalent Fractions

Here is another page of equivalent fractions. One part of each pair of fractions is missing and the missing numerator or denominator needs to be entered. Remember, equivalent fractions are fractions which have the same overall value.

One interesting way to check whether two fractions are equivalent is to carry out a couple of multiplications; what is known as cross multiplication. To check whether a/b is equivalent to c/d just multiply a by d and then multiply b by c. If the two answers are equal then the fractions are equivalent. This is a really good way to check to see whether the answers given are correct.

Equivalent fractions (pg 2)

Resource of the Week: Reflective symmetry

There is quite a lot of work done in Year 6 on symmetry and the subject often comes up in the Key Stage 2 SATs.

Some of this involves important vocabulary and by the end of year 6 children should know and be able to read, write and use the following quite tricky words:

Mirror line,  line of symmetry,  line symmetry,  symmetrical,  reflect,  reflection,  translation, axis of symmetry, reflective symmetry.

Also they should be able to test for symmetry using a mirror and by folding.

Children are expected to sketch the reflection of a simple shape in a mirror line where none or only some of the edges of the shape are parallel or perpendicular to the mirror line.

This might seem easy, but actually prove problematic to many children. A small mirror or tracing paper can be a great help with this.

Year 6 maths worksheet: reflective symmetry

Year 4 maths worksheet: Tenths of rectangles

A good way of working with decimals is to use shapes which are divided into ten equal parts. The shape is one whole unit and each part is one tenth, which can be written as 0.1.

This page has a selection of shapes and asks the child to write down the amount that has been shaded. Where all parts of a shape have been shaded this counts as ten tenths, or one whole one.

Whilst printed pages nearly always show the decimal point situated on the line most schools show it as half way up the line: the most important thing is that it shows up clearly.

This page can be found in our Year 4 maths worksheets in the Counting and Number category.

Tenths of rectangles (1)

Year 1 maths vocabulary

If a child does not respond to a mathematical question it may be because they do not understand the words or instructions used. Another difficulty can arise when a mathematical term has a different meaning in everyday English eg ‘table’.

In the Year 1 maths category there is an excellent list of the vocabulary children need to understand and use in year 1. For example, the following list has the new words that they should come across in school during year 1 to do with calculating and solving problems.

Words to do with calculating and solving problems:

plus                                     near double

how much more is…?     how much less is…?

subtract                             minus

half                                     halve

equals                               sign

number sentence

operation

There are similar lists for calculating, measures and position. These words can be printed larger so that they can be used as ‘flash cards’ or displayed on the wall.

Go to the Year 1 vocabulary lists.

Year 3 Mental Arithmetic: Sets 5 and 6

This week I have published the next two sets of mental arithmetic questions for Year 3. They concentrate on one-step problems, recalling addition and subtraction facts up to 20,adding and subtracting multiples of ten and knowing 5 and 4 times tables.

There are several ways these questions can be used and how children answer them. It is a good idea sometimes to use a set of digit cards, so children can hold up the answer. Number fans serve a similar purpose. Sometimes you might want the answers to be called out, or to be written down. The question sheets can be used for this purpose.

Y3 mental arithmetic sets 5 and 6

Year 5 maths: Written multiplication

Here we have a second page of questions  which are an intermediate step in the progress towards developing an efficient, standard written method of multiplication. It presumes a good knowledge of tables before starting.

This method breaks the task down into four parts. For example: when multiplying 538 by 4, the four parts are:

1. multiply 500 by 4

2. Multiply 30 by 4

3. Multiply 8 by 4.

4. Add the four answers to reach the final answer.

Whilst this is a good method I prefer to work in the reverse order of starting with the units, then the tens and finally the hundreds, although if the child understanding what is happening it makes little real difference.

Multiply a 3 digit number by a 1 digit number (2)

Maths Resources: Written Addition

One of the most popular parts of the site for parents is our Free Maths Worksheets: Four Rules pages on written addition.

Many parents think that the methods they were taught at school (and for many this would be in the mid 1990s) are different from today. This is only partly true. Since the onset of the Numeracy Strategy and later the Primary Framework for Maths the emphasis has been on preparing children properly so that they understand the written methods they use. So there is a lot of preparation work and methods often called, ‘Moving towards the standard written method’ that may not be familiar to parents, but the end result is pretty much the same. It is these intermediate stages which some parents find puzzling.

The standard written method is to lay out the sum vertically, with the numbers to be added under each other. The units are added first, then the tens and so on. We have several worksheets which explain this method in full.

Go to Written Methods of Addition