Here's an example:
3 + 5
7 + 6
Add 3+5=8. Write down the answer or store it in memory. Add 7+6=13. Now enter the 8 from the first answer and then divide it by entering the second answer to get x=0.62.
Press 3 then the ENTER key. Press 5 then the + key. Press 7, and then ENTER. Press 6 then the + key. Note that the answer to the second sum is displayed. Now here's the magic part. Touch the divide key and the calculator gives the answer, 0.62.
13 strokes, not counting the effort to write down or memorize the first answer while you calculated the second answer.
9 strokes, and no need to write anything down.