Calculator
Do the math. Keep the reasoning next to it.
Every line is a calculation and a note. Type the numbers, then say what they mean. The answer sits on the right, in order, so anyone can follow how you got there. Name a result and reuse it lower down.
Saved in this browser. Nothing leaves it.
Shortcuts. Tab inserts the previous answer. prev or pr = previous answer. total = sum of the lines above. rent = 28 x 1950 names a result you can reuse. Click any answer to copy it.