Subtraction often only gets taught as removal. Necessary but not sufficient. Subtraction as distance is critical.
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@pwharris Two ideas this time: factor dosey do: (2 x 2 x 2 x 3) x (3 x 5 x 5) can be rearranged and multiplied to become 10 x 10 x 9 x 2 which is 1800. The other is to half and double twice 12 x 1500 to 6 x 3000, all to equal 1800.
@pwharris I thought of 125% of 160, which is 160 + 40 thinking of 100% and 25% respectively. This makes 200, but since we are not dealing with percents, the result is 200 x 100, or 20,000
@pwharris How many twelfths in 3/4? A clock is a wonderful tool for this one. A clock splits nicely into 12 twelfths and 3/4 of a clock has 9 twelfths.
@pwharris I saw 3/2 as one whole and a half. If I sectioned the whole into sixths, I would have 6 and the half would have 3 sixths. Therefore there are 9 sixths in 3/2.
@pwharris With multiplying fractions, I find it intuitive to say "of" for the multiplication sign. It makes sense to say "one half of" or "one third of" a number.
@pwharris Thanks to @pgeerkens , I tried difference of squares. The sum of the factors is 60. And half of that is 30. With the fact that 44-30=30-16, then I can set up 30^2 - 14^2, which is 900-196. 900 - 200 is 700 and add 4 back to get 704. Cool!
@pwharris I was also interested that when I altered the question to 7 x 72, that it was comparable to 52 weeks + 20 weeks. This works out to approximately 365 day + 140 days. This gets to 505 which is only one away from the answer 504.
@pwharris My first thought was to double and half to make the problem 7 x 72. I know 70 weeks is 490 days and I then add two more weeks to arrive at 504 days. Weeks for the win!