median
don steward
mathematics teaching 10 ~ 16

Thursday 19 January 2017

mirror multiplications

first, a few examples indicating that 'mirror' multiplications do not usually have the same answers




















some of these are close results

and they can be the same ...
253 x 64 = 46 x 352



further examples of mirror multiplications with the same answers




















a powerpoint for this task includes a step by step calculation for 253 times 64

considering how mirror multiplications can have the same solutions:

as an initial step:
how can the lead and final digits of the two multiplications be made to be the same when they cannot be the same numbers?

for the number in the centre of the 3-digit number:
a grid method (expanded) representation shows how equal answers are obtained for the examples above
what is their common property?


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