The Mind Creative March 2014
Rule: Starting from the rightmost digit, double each digit
and add the neighbour. If the answer is greater than a
single digit, simply carry over the extra digit (which will
be a 1 or 2) to the next operation. The remaining digit is
one digit of the final result.
Example: What is 316 x 12?
Consider the following:
The number is 0316
The digit 6 has no right neighbour
The digit 1 has neighbour 6
The digit 3 has neighbour 1
The digit 0 (the prefixed zero) has neighbour 3
Hence the calculations will progress (from right) as follows:
6 x 2 = 12 (2 carry one)
1 x 2 + 6 (the neighbour) + 1 (the carry) = 9
3x2+1=7
0x2+3=3
The answer is 3792
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