For a given universal set , each subset A of  satisfies the idempotent laws of union and i...

For a given universal set , each subset A of  satisfies the idempotent laws of union and intersection,

(a) Are there any real numbers that satisfy an idempotent property for addition? (That is, can we find any real number(s) x such that x + x = x?)

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(b) Answer part (a) upon replacing addition by multiplication.