7 of 10. I underestimated Asian (Eurasian?) continent area by factor 4 (safety margin one order of magnitude), quantity of US dollars by factor 10 (safety margin 3 orders of magnitude) and volume of gr. lakes by factor 0.1 (safety margin 3 orders of magnitude). Other safety margins were 3 orders of magnitude for Titanic, Pacific coast (fractal-like curves can be very long), book titles, and 0.5 from mean value for others. Sigh, I thought I'll have 90%.

Hm, I estimated area of Asian continent as area of triangle with 10000km base (12 timezones for 20000 km and factor of 0.5 for pole proximity) and 10000km height (north pole to equator), and lost one order of magnitude in calculation.