Tere wrote:
I got 9 out of 11. I din't do well with the 30 divided by 1/2. I still don't understand it!

30 / 1/2 is like 30*2.
When you divide a number (call it a, for instance) by an integer, you get a number which is smaller than a. It is like when you cut a cake : if you cut it into several parts for several people, each part is smaller than the cake.
So dividing by one means keeping the cake as it is. a divided by one is a.
But if you divide by something which is smaller than one, then you get something which is bigger than a, because instead of cutting it, you make another cake. In this case, you can visualize it as : "1/2 means I have half the quantity of cake needed for all the guests." So 30 divided by 1/2 is like 30*2 = 60.
Add 10 and you get 70.
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Nicolas (spark).