This book discusses the defect pf the current practice of shariah economy viewed from the fact that muslims apparently have forgotten the use of the islamic calendar as the basis of the accounting system of their businesses. The use of the Gregorian calendar as a replacement of the inexistence of a reliable islamic calender seems to have created trivial problems. However, this book will show, the ostensibly trivial problem has actually snowballed into a huge problem that all muslims accounting system has inadvertently created accumulated zakat payment deficit. By reading this book, it is of paramount importance that muslims become aware of the past mistakes in neglecting the use of the islamic calendar in our worldly lives.

The neglected use of the islamic calendar in Muslims business is actually rooted in the difference of Muslims in Perceiving Rasul's command to see the crescent (hilal) as an authentic mark to commence an islamic month to costruct an islamic calendar. On the one hand, some Muslim clerics argued that the hilal must be visible to human eyes as this had been the practice of the Rasul and his companions in that era. This argument has made the contruction of an Islamic alendar is impossible in the first place, otherwise the Islamic calendar will only be valid exactly one month. Every month, Muslims has to conduct the moonsighting. Other clerics despite being outnumbered. On the ither hand, believe that the prerequisite to sight the hilal in Rasul's era was actually indispensible owing to the fact that the moonsighting was the only available technique to confirm the presence of hilal in that era. The latter group is of the opinion that the advent of astronomical calculation has actually been able to replace the moonsighting method entirely in confirming the presence of the hilaL. This latent argument has been goin on for hundreds of years without any significant progress and solution. In the mean time. Muslims hence pragmatically rely on the Gregorian calendar for their business accounting system.

In order to support the hypothesis, the author develops the algorithm an uses different data sets. All the research outcomes confirm that muslims actually reserves a huge potential of power for eliminating poverty especially in Muslim countries if they are willing to rectify their past mistakes due to wrong conception in applying wrong financial system, The unconsciously embezzled zakat might stay at an astronomical figure of trilions of us dollar. This is a concealed potential of Muslims in the global economic development.