Coming soon: mental arithmetic on subtraction and division

girlface1smallGood luck to all those taking SATs.

We have some great mental arithmetic stuff coming up soon, including worksheets on how to divide by 4 mentally and subtracting single digits from multiples of 100 or 1000. Another interesting post will be on rules of divisibility for the numbers 4 and 5.  Also we will be looking at the relationships between addition and subtraction and multiplication and division as well as the second in our series of fractions worksheets for Year 2 children. Plus much more! Watch this space!

Mental arithmetic: Dividing by 4

divide-by-4-1A nifty way of dividing a number by 4 is to halve the number and then halve again. This method is much easier with even numbers and, of course, whole multiples of 4, but can be used for most 2-digit numbers – just the remainders become tricky. All these questions are multiples of 4 so should be relatively straightforward. Knowing these ‘tricks’ can give children a lot of confidence and can also be a useful way of checking answers which have been calculated on paper, or even on a calculator, to ensure that the answer is sensible.

Divide by 4 mentally

Multiply by 9 mentally (1)

multiply-by-9-mentally-1You can multiply most 2-digit numbers by 9 in your head. The most efficient way is to multiply the number by ten and then subtract the number. For example:

45 x 9

First of all multiply 45 by 10 which is 450.

Then subtract 45 from 450 which is 405.

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

Multiply by 9 mentally (1)

Maths worksheet: Moving towards a standard method of division

division-2-by-1-digit-2This is the second division worksheet which looks at the intermediate stage between mental methods of division and a standard method. I am not a great fan of this method but it is used in many schools.

The first thing to do, as always is to make an estimate of the answer so that any silly slip ups in the calculation may immediately come to light. The second stage is to  find a multiple of ten that can be taken away – in all these examples and questions this multiple is 10 itself. Then we move towards the more traditional method of asking ‘how many…. in….’.

If you are just moving towards doing division, perhaps in Year 3/4 it is certainly a method which can be used.

Division 2 by 1 digit (p2)

Standard written subtraction with zeros.

standard-subtraction-3Here is another maths worksheet which looks at the standard method of subtraction, often called decomposition. Once again the numbers are small, and many children will be able to work the answers out ‘in their heads’. However, it provides good practice with the method, whilst not having to worry too much about the size of the numbers involved.

All these subtraction questions have a zero in the number which is being taken from. This can sometimes cause children a few problems: watch out for the mistake of saying ‘0 – 8 is 8’.

Once these have been mastered it is only a short step to being able to successfully complete any subtraction sum.

Standard subtraction with zeros

News: Head teachers to write to parents about SATs.

Head teachers will shortly be writing to all parents of children who would normally be taking the SAT tests next year. The National Association of Head Teachers want to end the tests as they say that they narrow the curriculum and interfere with proper education as teachers are forced to teach to the test.

The Department for Children, Schools and Families has said previously that head teachers have a statutory duty to administer the tests, so would be breaking the law if they did not.

It is not really the tests which are a problem as they only take about three mornings out of the school year, but it is the publishing of the tests, which forces Head Teachers to believe that they need to practice for them, give homework on them, have after school clubs etc so that the school does not ‘fail’.

Coming soon: subtraction, division and more

jpg-sun701Well, it’s May Bank Holiday so I am going to have a little break and a walk along the beach. But coming up later this week will be some great worksheets on using the standard method of subtraction and division, plus some tricky mental arithmetic pages on adding decimals and multiplying by 9 mentally.

Enjoy the sunshine!

Multiplying decimals 1

multiplying-decimals-1The standard short method of multiplication can be used when multiplying a decimal by a single digit. Children need plenty of practice with this before moving on to working with decimals.

The key to success with these is to place the answer in the correct columns and the best bet is to put the decimal point in first. Think of the decimal point as a fixed point, therefore the point in the answer should be immediately above the point in the question. Apart from that, these should prove to be straightforward.

This maths worksheet shows the method and then gives 12 questions to practice.

Multiplying decimals (pg 1)

Year 5 maths worksheet: square numbers 1

square-numbers-1This worksheet has a 10×10 multiplication square which is a brilliant aid to helping with tables, but it is also excellent for showing the pattern of square numbers from 1 to 10.

A square number is made by multiplying a whole number by itself. eg 4 x 4 = 16.

16 is a square number.

It is quite useful to learn the first 10 square numbers off by heart:

1, 4, 9, 16, 25, 36, 49, 64, 81, 100.

We will look more closely at square numbers later.

Square numbers (pg 1)

News: More technology in schools

monitor1Teachers are going to be given extra training so that they can keep up with their computer expert pupils. Under the latest proposals the primary timetable should be more flexible and the internet should be embedded within it. Pupils will be encouraged to use websites such as Google Earth, Wiki and Mathsblog (well why not?) to study the new Areas of Learning.

These Areas of learning are:

Understanding English, communication and languages
Mathematical understanding
Scientific and technological understanding
Human, social and environmental understanding
Understanding physical health and well-being
Understanding the arts and design.

Teachers will need to have training on the latest developments on the web and become more aware of the fantastic possibilities which are now available. Good.