In the republic of doppelganger, the currency is the ditto. during 2015, the treasury of doppelganger sold bonds to finance the doppelganger budget deficit. in all, the treasury sold 50,000 ten-year bonds with a face value of 100 dittos each. the total deficit was 5 million dittos. the doppelganger central bank reserve requirement was 20 percent and in the same year, the bank bought 500,000 dittos' worth of outstanding bonds on the open market. all of the doppelganger debt is held by either the private sector (the public) or the doppelganger central bank. the combined effect of the treasury sale and the doppelganger central bank purchase on the total doppelganger debt outstanding is a change in overall debt and, in particular, the debt held by the private sector increases bythe treasury sale will change the money supply in doppelganger dittos. assuming no leakage of reserves out of the banking system, the effect of the doppelganger central bank purchase of bonds on the money supply is a change of .