- Trachtenberg Technique v2
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- Lijsten: 0 + 0 Beoordelingen: 0 Recensies: 0
- Punten: 0 + 0 Versie: 7.0 The Trachtenberg system v2 is a system of rapid mental calculation. The system consists of a number of readily memorized operations that allow one to perform arithmetic computations ... ⥯
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