Here is where I'm thinking a problem may lie with the wording:
"The difference must be the same as one of the decimals in the problem."
It's kinda subtle, to me, but that wording caused me to first think that all of the numbers in the problem must be written as decimals. What if it were to say the following, instead?
"The difference must be the same as a number in the problem."
I interpret the following (paraphrased) instruction kinda literally: Use each [digit] exactly once to write a decimal-subtraction problem
In other words, the problem should contain each digit once, and a "decimal-subtraction problem" is any problem that involves subtraction and at least one decimal number.
If somebody were to do the subtraction, their result would be a decimal number in the exercise.
I'm thinking that the specific "number sense" that this exercise is intended to test is this: If we subtract zero from a decimal number, we get the decimal number back again. In other words -- and there's probably some named property for it -- subtracting zero from anything changes nothing.
So, here's my guess, in symbols: a.bcde - 0 = a.bcde
Cheers :cool:
