There’s no reason to expect that the sum of the balances remaining would be equal to the initial amount. If you spend in 1$ increments, the balances would be 49, 48, 47,… which sum to much larger than 50. If you spend 49$ followed by 1$, right away, the balances sum to 1$, which is much less than 50. This particular example has been “cooked” to give a value of 51. You can cook up another example to give whatever value you want.
There’s no reason to expect that the sum of the balances remaining would be equal to the initial amount. If you spend in 1$ increments, the balances would be 49, 48, 47,… which sum to much larger than 50. If you spend 49$ followed by 1$, right away, the balances sum to 1$, which is much less than 50. This particular example has been “cooked” to give a value of 51. You can cook up another example to give whatever value you want.