If you spend one dollar at a time, the total amount of money you have left can be more than 1000, and the amount behind is different every time and cannot be accumulated.

Suppose you originally had a 50 yuan, spent A, B, C and D on the first, second, third and fourth things, and finally left 0, then 50 = A+B+C+D. After buying the first thing, the remaining: 50-A; Remaining after purchasing the second item: 50-a-b; Remaining after purchasing the third item: 50-a-b-c; Remaining after purchasing the fourth item: 0;

So the sum of the remaining money is:150-3a-2b-c.

Because a, b and c are all uncertain numbers, the remaining money adds up to countless results. It means that the sum of the remaining money is related to the amount of money spent each time, but it is not equal to the original amount of money.

The difference between the questions is just 1, which is purely a numerical coincidence ~