Press the square root button twice. Press the multiplication button. Press the square root button twice. Press the multiplication button. Press the square root button four times. Press the multiplication button. Press the square root button eight times. Press the multiplication button... This process is continued until the number does not change when the multiplication button is pressed, since the repeated square root gives 1 (this means that the solution has been determined to as many significant digits as the calculator can handle). At this point an approximation of the cube root of the original number will be shown in the display.