Original sentence: They intuitively see their addition of a 1 to the last 9 in 0.999… as carrying all the 9s into 0s and leave a 1 in the ones place.When asked what 1 − 0.999… might be, students may use the number "0.000…1"
Edited sentence: When asked what 1 − 0.999… might be, students often invent the number "0.000…1".Whether or not that makes sense, the intuitive goal is clear: adding a 1 to the last 9 in 0.999… would carry all the 9s into 0s and leave a 1 in the ones place