One of the tricks I picked up from Number Sense competitions is to conceptualize a product as a difference of 2 squares, i.e. 22*28= (25-3)*(25+3) = 25^2 - 3^2 = 625 - 9...
I just thought of a cute reversal, though. We could envision a squaring, as a product
plus another square... so, 25^2 = 22*28 + 3^2 = 616 + 9.
Thinking along that line, 6^8, then, is 1296^2 = 1292*1300 + 4^2.
So, is it easier to figure, in your head, 1296*1296 or 1292*1300?
I think the latter could be easier, as there's less digits to juggle.
No comments:
Post a Comment