1) variable
2) value
3) absolute value (maybe)
4) natural numbers
5) whole numbers
6) integers
You would take answer you got for how much they spent and multiply the answer by 2.
The problem statement is cut off, but it appears you have 6 rods of 10 cubes and 6 unit cubes that are colored red.
6·10 + 6 = 66 . . . . standard form number
In words, this number is ...
... sixty-six
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The digits in the thousandths and hundredths places are both zero in this number. They are exactly equal, or you could pick any number you like and say that one of them is that number times the other of them. 0 = 43×0, for example.
The place value of the 1/1000ths place is 1/10 times the place value of the 1/100ths place, so if you have the number 66.322, the 2 in the thousandths place has a value of 2/1000, which is 1/10 times the value of the 2 in the hundredths place, which is 2/100.
Its helps you like when you want to take away something it help you in a negative way