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Get handy hints on multiplication, division, factors, and more in this guide. Learn mental & written methods to help your child succeed in math. Discover efficient ways to teach and support your child’s mathematical journey.
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Maths Workshop for Parents Handy hints on terminology and calculation methods
Intro • Theory • Methods for multiplication and division • Place value multiplication and division • Order of Operations • Factors and Multiples • Prime Factorisation
Do it your way! • 25x19 • 5% of 86 • 248-99 • 103-98 • ½ of 378 • 1+2+3+4+5+6+7+8+9+10+11=
Mentally add and subtract anypair of 2-digit numbers • For most children during the latter part of year 3 • Children will be using a variety of mental methods by this time
Mental first • 56+ 29 or 56 +29 • Children cease to “say” the numbers, seeing only digits in columns e.g. “6 add 9” instead of “56 add 29”
2000 -102 This is most sensibly done by counting back, not by decomposition
25x8 or 25 x 8 • Children relying on written procedures forget how much they can do mentally. 25x8 is double 25x4
The calculating repertoire “Brain paper”: • Mental recall of number facts • Mental methods of calculation Real paper (and use of calculators) • Jottings to record mental calculations • Informal written methods • Standard written methods
Expanded Written Methods Standard Written Methods Calculator Mental Calculations with jottings Informal Methods Mental Recall The calculating continuum
The calculating repertoire • Children constantly move up and down the continuum • Learning a new method of calculating does not mean other ways are no longer relevant • Children should always be looking for calculations they can do wholly or partly mentally
A structured approach to calculation An approach based on the skills of mental calculation: • Remembering number facts • Using known facts to derive new ones • Familiarity with the number system and relationships between numbers • Having a repertoire of mental calculation strategies • Understanding of the four operations and how they are related
Addition and subtraction • Partitioning is an important strategy children must learn • A number line is a method of informal calculation that works for any size of number, for both operations. • Knowing 33+ 25 = 58 leads to the following: 25+ 33 = 58, 58-33 = 25, 58-25 = 33 25+ ? = 58 ?+? = ?+?
Multiplication and division • Multiplication is repeated addition, division is repeated subtraction • Doubling, halving, partitioning, and multiplying by 10, 100, 1000 are essential mental strategies • 3x4=12 leads to 4x3, 12÷3, 12÷4, 6x4, etc, 30x4, 300x4, 120÷4 etc • Children need to see facts as arrays
Moving from informal to formal methods • At every stage, teachers first use examples that children can easily do mentally • Children then see how the steps in a written procedure link to what they do in their heads • They then move to using numbers that cannot easily be dealt with mentally, including money and decimal numbers • Partitioning and place value are crucial concepts and estimation of size of answers is essential.
Long multiplication • Grid method • Compact / formal / column method
Long division • Chunking • Bring down remainders (DMSBR)
Place value multiplication and division • Move digits one column to the left to x10 • Move digits one column to the right to ÷10 • Essential skill • Measure conversions • Percentages
Order of operations (BIDMAS) B = brackets I = indices D = division or M = multiplication A = addition or S = subtraction 32 + 4 x (7 – 2) = 32 + 4 x 5 = 9+ 4 x 5 = 9+ 20 = 29
Factors and multiples • You multiply two or more numbers together to find their product. • The product of 2 and 7 is 14: 2 x 7 = 14 • 14 is a multiple of 2 and is also a multiple of 7 • Any whole number can be written as the product of two factors.
Factors and multiples • You can list all the factor pairs of a number or • You can write the factors in a list • If there are only two factors, the number is a prime number • A square number has an odd number of factors
HCF and LCM • Highest Common Factor • Lowest Common Multiple
Prime Numbers and Prime Factorisation • Important to learn divisibility rules • Try to recognise primes up to 100
Open Forum • Any specific queries? • Future workshops?