Spin (physics) discrete angular momenta despite having no orbital angular momentum. In some ways, spin is like a vector quantity; it has a definite magnitude, and it has a "direction" (but quantization makes this "direction" different from the direction of an ordinary vector). All elementary particles of a given kind have the same magnitude of spin angular momentum, which is indicated by assigning the particle a spin quantum number. The SI unit of spin is the (N·m·s) or (kg·m·s), just as with classical angular momentum. In practice, spin is given as a dimensionless spin quantum number by dividing the spin angular momentum
Order of magnitude <math>0.5, perhaps because the arithmetic mean of formula_5 and formula_12 approaches formula_13 for increasing formula_14. This definition has the effect of lowering the values of formula_4 slightly: Yet others restrict formula_10 to values where formula_17, making the order of magnitude of a number exactly equal to its exponent part in scientific notation. Orders of magnitude are used to make approximate comparisons. If numbers differ by one order of magnitude, "x" is "about" ten times different in quantity than "y". If values differ by two orders of magnitude, they differ by a factor of about 100. Two numbers of the same