| Trachtenberg Speed System of Basic Mathematics, Paperback - Jakow Trachtenberg • elefant.ro | 68.55 RON |
| Trachtenberg Speed System of Basic Mathematics • libris.ro | 77.70 RON |
First developed during WW2, the Trachtenberg speed system makes possible high-speed arithmetical calcula tions with a remarkable degree of accuracy. The system has e ven been known to beat computer calculations - in some insta nces - in terms of speed
