When using the iPhone Calculator app, if you type a wrong digit you may be inclined to press C, which deletes the whole number. However, if you swipe left or right in the box where the number is located, you can delete only the last digit.
Repeat last command in Excel Pressing F4. in Excel repeats the last command. An example I found on Reddit; if you select a cell and highlight it yellow, you can then highlight any other selected cells yellow by pressing F4. On an Mac press Command + Y.
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