If you want to keep 100% accuracy in calculations without writing down all your decimals, use variables. They can store any value, even after the calculator is turned off.

Step 1: carry out any calculation you want. In this example I found the square root of 17 plus 2π.

Step 2: press Ans (to bring the value to the top), then press Shift+RCL. The STO label should appear.

Step 3: without pressing shift or alpha, press the button below the letter you wish to assign the answer to. For example, pressing the sin button will assign your answer to letter D.

The arrow confirms that the value has been assigned to letter D

The available letters (you can only assign one value to each)

Step 4: That’s it! You can now use the stored value by pressing alpha, then the button corresponding to the letter you chose.

An example calculation using the variable we assigned.

note: to change the value stored in a letter, just repeat this process and it will override.