The Tarski number of a non amenable group is the smallest number of piecesneeded for a paradoxical decomposition of the group. Non amenable groups ofpiecewise projective homeomorphisms were introduced by Monod, and non amenablefinitely presented groups of piecewise projective homeomorphisms wereintroduced by the author in joint work with Justin Moore. These groups do notcontain non abelian free subgroups. In this article we prove that the Tarskinumber of all groups in both families is at most 25. In particular wedemonstrate the existence of a paradoxical decomposition with 25 pieces. Our argument also applies to any group of piecewise projective homeomorphismsthat contains as a subgroup the group of piecewise $PSL_2(\mathbb{Z})$homeomorphisms of $\mathbb{R}$ with rational breakpoints, and an affine mapthat is a not an integer translation.
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