hp 10bII - Standard Deviation
One way to verify that your calculator is working properly is to follow the example on Page 89. To get mean, you should use the orange shift key followed by [ 7 ] and the answer 3.5 should display.
To get Standard Deviation, press orange shift key followed by [ 8 ] and you should get the answer 0.85.
I have attached the quick reference screen print from Page 89 for your HP 10bII Manual.

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