Quote:
Originally posted by stomachmonkey
Exactly. It's a better foundation for actually learning "formulas" vs the old multiplication drills that only taught you to memorize the answer.
For me it's not 15x17, it's 300-45. I "see" 15x20-3x15.
Ever watch people try to make change? You can tell the ones that have been taught to calulate vs memorize.
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OK one more variant as I've always done this. To me this factoring,nothing more, in this one I see 150+70+35
edit: although the correct solution to the original post is NOT 360