Corrections in calculations on a modern "textbook" display calclator

Modern calculators that have a real textbook like display can offer advantages not only to inputting formulas, but when realising a mistake several steps down the line. Here is one such calculator that, when an error is corrected a few steps back, the updated results are automatically flowed down.

Here is the problem statement:

The respondent has come to the second part and written down some equations and decided to calculate it on the calculator. When the last answer seems a bit strange, an error is found in the earlier entry, corrected and the correct answer is immediately visible at the last calculation.