Magic numbers For example: 1.US per-capita GDP,1995 prices ·$3300in1870 grew by a factor≈I0 "$32500in2000 →average growth rate: g=[ln(32500)-ln(3300)]/130=1.75%. 2.China with a annual rate as high as 10%, which accumulates to a factor of 17.45 over the 30-year period.Magic numbers  For example: 1. US per-capita GDP, 1995 prices $3300 in 1870 $32500 in 2000 average growth rate: g = [ln(32500)-ln(3300)]/130=1.75%. 2. China with a annual rate as high as 10%, which accumulates to a factor of 17.45 over the 30-year period. grew by a factor ≈ 10 Chyi, Macro I, 2006