Hi snailbrain:
Multiplication is simply multiple additions
Counting up at intervals - is frequently used in YR & Y1
Often starting with even and odd numbers and counting by twos.
by twos (or even numbers) 2, 4, 6, 8, 10....
odd numbers 1,3, 5, 7, 9, ....
Counting by 5s and 10s is often next:
5, 10, 15, 20,....
10, 20, 30 , 40....
and some schools also introduce counting by 3s.
Why?
Well these are at the root of most times tables families.
If you know how to count up to 100 - formally introducing the x1 table is a doddle. Anything x 1 is itself. 99,999 x 1 = 99, 999. EASY.
If you know how to count by twos - formally introducing the x2 table is a doddle.
2 x 1 = 2
2 x 2 = 4
2 x 3 = 6
2 x 4 = 8
etc...
at some point this will also be explained as doubling.
Doubling is key because x4 and x8 (and in fact x 6 and x12) all can be worked out if you know how to double.
x4 - 4 x 4 is the same thing as doubling (2 x 4) = 2 x 2 x 4 = 16
x8 8 x 4 is the same thing as doubling (2 x 4) and then doubling it again - or 2 x 2 x 2 x 4
If you can count by 3s again learning the three times table is a doddle:
3 x 1 = 3
3 x 2 = 6
3 x 3 = 9
3 x 4 = 12
etc......
Once you know your 3s - x 6 is just doubling your x3 table:
so 6 x 3 is the same thing as doubling (3 x 3) = 2 x 3 x 3 or doubling (9) = 18.
If you know your six times table - then the same method works for x 12 - just double.
So if you know 4 x 6 = 24 then you know 4 x 12 = double (4 x 6) or double (24) = 48
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Now if you factor in that you should already know x5 & x10 - see what you've achieved:
x0 (let's take that as given - anything x 0 - 0)
x1
x2
x3
x4
x5
x6
x8
x10
x12
so that leaves x7 (which is just something you have to memorise - save it for last and you need only memorize 7 x 7 = 49 - because you've learned it for all other tables).
x9 has two tricks.
flip your hands palm upwards so so your thumbs are at each end - starting from left thumb number them 1 - 10. Now fold down the finger you're multiplying 9 by. So 4 x 9 - results in the left ring finger folding down - you'll have 3 fingers up to the left of the folded 4th finger and 6 fingers up to the right = the left fingers = tens and the right fingers = units. So the answer to 4 x 9 is 36.
The pattern:
1 x 9 = 09
2 x 9 = 18 number in the tens column is always one less
3 x 9 = 27 than what you're multiplying 9 by
4 x 9 = 36
5 x 9 = 45
6 x 9 = 54 both digits always add up to 9
7 x 9 = 63
8 x 9 = 72
9 x 9 = 81
10 x 9 = 90
doesn't work beyond x10.
11 x 9 = 99
12 x 9 = 108
however the all digits add up to 9 thing still works
11 x 9 = 99 and 9 + 9 = 18 and 1 + 8 = 9
12 x 9 = 108 and 1 + 0 + 8 = 9
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x11
well it's easy up to and including x 9 - just write whatever you're multiplying 11 by down 2 times.
1 x 11 = 11
2 x 11 = 22
3 x 11 = 33
and so on....
from 10 there is a trick.....
take the number you're multiplying 11 by and separate the first and second digit. In the middle add the two digits together. This may involve carrying but the trick always works.
For example:
15 x 11 - trick 1 - (1+5) - 5 = 165 (check on calculator - it works).
19 x 11 - trick 1 - (1 + 9) - 9 = 1 - (10) - 9 (now we can't have two digits in the middle column so have to carry)
so that's 19 x 11 = (1 + 1) - 0 - 9 = 209 (try the calculator it works).
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That leave 7 x 7 = 49. you know all the rest - and all tables 0 - 12 are now learned.
HTH