Quote:
Originally Posted by needforspeed
Seriously don't understand how this is done
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It really is very simple maths, NFS!
Let's use a bit of algebra!
You pick 2 digits, so let's say the number is written as 'ab'.
'a' must be at least 1 & b could be 0-9, so
'ab' actually equals (10 x a) + b
Take away (a+b):
(10 x a) + b - (a + b) = 9 x a
So, you' re only ever left with the 9-times table- all the symbols are the same for those numbers, upto 9 x 9 ie 81.
They do change each go, but they still stay the same for all multiples of 9!
Viv