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Fuzzy counterpart of real numbers, called fuzzy numbers (reals), are investigated. Their membership functions satisfy conditions similar to quasi-convexity. In order to operate on them in a similar way to real numbers revised algebraic operations are introduced. At first four operations between fuzzy and real numbers are in use in a form suitable for their algorithmisations. Two operations: addition and subtraction between fuzzy numbers are proposed to omit some drawbacks of the corresponding operations originally defined by L. A. Zadeh with the help of his extension principle.