Transcript Our Lady`s Primary School

Our Lady’s Primary School
Hallowe’en Video Conference
Part 2
Times Table Challenge
• We have been using our knowledge of the
times tables to solve problems
• The times table was given in the form of
letters, such as:
C x A = BF
• The challenge for us was to work out which
times table it was, then work out what
number each letter represented.
Here is the times table:
J x J = HJ
J x D = HC
J x G = AJ
J x I = DC
J x B = AC
JxF=J
J x E = DJ
J x H = FC
J x A = FJ
How did we solve the
problem?
• First, we noticed that there was only one
single digit answer. This meant that it
couldn’t be the 2,3 or 4 times tables.
• Then we noticed a pattern in the answers –
they all ended with either J or C. Which
times table answers end with only 2
different digits?
• There is only one - the FIVE times table!
• Now we just had to work out what number
every letter stood for.
First, we looked at:
JxF=J
We knew that a number multiplied by
1 is itself, so F =1;
Then we looked at
J x J = HJ
We knew that 5 x 5 = 25 and that
J=5, so this meant that H=2.
We carried on like this and
eventually found all the numbers
which the letters represented.
We have been looking
at the two times table:
• We have learned what ‘multiple’ means
• A multiple of 2 divides exactly by two with
none left over.
• We have found that all multiples of two are
even
• We know that all even numbers end in 0, 2,
4, 6 or 8.
• We coloured all the multiples of 2 on a
number square.
We have been looking at
quick ways to spot
multiples of 2, 5 and 10:
• We found out that all multiples of 10
end in 0;
• For example:
• 50, 80, 120, 450, 100, 1000 are all
multiples of ten.
• We coloured all the multiples of 10 on
a number square.
• We found out that all multiples of 5 end in
either 5 or 0;
• For example:
• 15, 40, 110, 205, 355, 500 are all multiples
of 5.
• We coloured all the multiples of 5 on a
number square
• We found out that all multiples of 2
end in 0, 2, 4, 6 or 8;
• We found out that all multiples of 10
are also multiples of 5 and 2.
• So the only digit we need to look at is
the units digit to spot multiples of 2,
5 or 10!
• On the same number grid, we coloured all
the multiples of 2 yellow, multiples of 5
blue and multiples of 10 red.
• Some of the numbers stayed yellow
• and some of the numbers stayed blue,
• but some of the numbers turned brown –
these are all multiples of 2 and 5 and 10!
Thank you for listening to our
presentation.
We hope to see you all again sometime.
Keep learning all your times tables!