In your Maths Lesson

IN YOUR MATHS LESSON

 

Why not check your sums by this fascinating method using digit sums.

  • Suppose you want to check that the simple
    addition sum below is correct.

              4  3
              3  2  +
              ___
              7  5

    We find the digit sums of 43, 32 and 75 and check
    that the first two digit sums add up to the third digit sum.

              4  3           7
              3  2  +       5 +
              ___           _
              7  5           3

    The digit sums are shown on the right and
    7 + 5 = 3 is correct in digit sums because
    7 + 5 = 12 = 3 (1 + 2 = 3)

    This indicates that the answer is correct.

    All sums, even the most complex, can be checked in this way.

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In Your Maths Lesson

 

It is worth noting (in case you want to check
subtraction sums using the nine-point circle) that in
digit sums  7-5=2, 6-6=0 and so on, but 3-4=8.
You can see this on the circle by starting at 3 and
going 4 jumps backwards round the circle.
Or, alternatively you can add 9 to the 3 so that 3-4
becomes 12-4, which is 8.


The advancement
and perfection of
Mathematics are
intimately
connected with the
prosperity of the
state
NAPOLEON

 

   

 

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