HEATHERSIDE JUNIOR SCHOOL

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MARVELLOUS METHODS FOR MENTAL MATHS

How do you know which type(s) of operation to use?

+ Addition +• add• total• sum of• altogether• plus• increase by• double• more than

- Subtraction –• subtract• take away• minus• count back / up• less than• fewer• find the difference• decrease by

VOCABULARY

x Multiplication x

• times• lots of• groups of• product of• multiplied by• multiple of• double• repeated addition• array

÷ Division ÷• share• share equally• equal groups of• divide• divided by• divided into• divisible by• remainder• factor • quotient• inverse

Progression in the use of number lines

Firstly, children count using a number track.

Then they use a numbered number line.

Next children begin to use number lines with regular interval markings and some or no numbers marked.

Finally, they use an empty number line to record their jottings.64 70

Children then use jottings to record numbers they have partitioned.

(linked to using a number line)

For example: 223 – 53 = 170

223 – 50 – 3 =?

223 – 50 = 173

173 – 3 = 170

They can also use a number line to add and subtract by counting back and up using the

nearest multiple of 10 and adjusting.

For example: 36 – 19 = 17

- 20

16 17 36 + 1

Complements to 10 & 100

1 3 7 5 5

4 70 15 15 90 10 6 4

7.6 6.5 9.3 3.5 0.7 2.4

My number bonds will help here!

Fun ways to learn the times

tables!

Quick recall games such as ‘Shoot the Sheriff’,

FizzBuzz & Chase the answer

Practice Gamese.g bingo, pairs, snap

Speedy TablesRace the clock and thenaim to beat your score !

Songs, raps and rhymes

Patterns and Rules of divisibilityDo you know the trick

your 9s?What do all multiples

of 2 end in? Practise, practise, do it again..practise a bit more…repeat,

try again..practise..haveanother go..

Tools to helpTables squares, number

lines, concreteapparatus, websites

By partitioning a number we can use known doubles of smaller numbers and then add

these together to calculate the answer.

Double 40 is relatively easy: 40 x 2 = 80

Double 7 is a known double: 7 x 2 = 14

Add these together 80 + 14 = 94

E.g. Double 47 is not a double that most people know off by heart.

Using known factsIf I know that 6 x 4 = 24, what else do I know?

How could I use my knowledge of the 2 times table to calculate the 4s or 8s?

How could I use this to make some calculations with decimals? Eg 6 x 0.4

The keepers at the zoo want to know how many monkeys they have. There are 16 enclosures, each containing 8 monkeys. How many monkeys are there altogether? Use your knowledge of the 8, 4 or 2 times tables to calculate the answer.

To calculate 17 x 6 I could do(10 x 6) + (7 x 6).How could I calculate 18 x 7?

Using inverse operationsFor every number operation (+ - x ÷) there is

an inverse operation.For example:

This can be used to calculate or check an answer:

7 x ? = 35

? - 143 = 29

53 + 48 = 101101 – 53 =48101 – 48 = 53

12 x 3 = 3636 ÷ 12 = 336 ÷ 3 = 12

? + 45 = 110

Round up or round down?

150 ÷ 60 =3 coaches needed Round up

High 5 rule

2 r30 or 2.5

There are 150 children and teachers going on a theatre trip. They need to travel from the school to the theatre in coaches. Each coach

can carry 60 children. How many coaches will be needed?

What key facts/knowledge would you need to know to help you solve these

questions?

James walked from 09:45 to 10:15. For how many minutes did he

walk?

A regular hexagon has sides of 8cm. What is its perimeter?

At the weekend I cycled 2.5km. My Dad cycled 200m further than me. How far

did Dad cycle?

Mental maths relies on children being able to calculate quickly

and accurately.

Please stay and have a go at some of the problems and

activities…can you use some of the mental

calculation strategies we have covered?