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We derive an explicit expression for geometric measure of entanglement forspin and other quantum system. A relation of entanglement in pure state withthe mean value of spin is given, thus, at the experimental level the localmeasurement of spin may allow to find the value of entanglement. The obtainedform of the measure is applied to the explicit characterization of bipartiteentanglement for $n$-qubit systems in the Werner state, Dicke state, GHZ stateand trigonometric states. In particular for Werner-like states the rule of sumsis found and it is shown that deviations from the symmetricity of such statesdiminishes the amount of entanglement. For Dicke states the maximal value ofbipartite entanglement is achieved when number of excitations is half of thetotal number of qubits in these states. For trigonometric states the bipartiteentanglement is maximal and does not depend on the number of qubits. We alsoconsider entanglement of discrete-continuous systems on the example ofentanglement of spin with continuous variables of electron. The relation ofentanglement with the mean value of spin is very useful for calculation ofentanglement. With the help of this relation we find in explicit form theentanglement of the one spin with the rest in a spin chain during the evolutiondetermined by the Ising Hamiltonian.

Geometric measure of entanglement for pure states and mean value of spin