Earlier calculations: ▲ and ▼

The calculator remembers earlier calculations. Do three calculations. Type 1, press , type 1, and press : 2. Then type 2, press , type 2, and press : 4. Then type 3, press , type 3, and press : 6. Press : the display shows $\displaystyle 2 + 2$ again, with its answer 4. Press again for the first one: 2. The down key goes forward. The history is erased when you press ON, change the mode or the display format, or reset the calculator.

▶ Watch this step in the video (21:35)