Successful mining took time and capital, particularly once most of the timber around the Klondike had been cut down. A realistic mining operation required $1,500  for wood to be burned to melt the ground, along with around $1,000  to construct a dam, $1,500  for ditches and up to $600  for sluice boxes, a total of $4,600. The attraction of the Klondike to a prospector, however, was that when gold was found, it was often highly concentrated. Some of the creeks in the Klondike were fifteen times richer in gold than those in California, and richer still than those in South Africa. In just two years, for example, $230,000  worth of gold was brought up from claim 29 on the Eldorado Creek.
Question: How many more dollars did a realistic mining operation require for ditches than for sluice boxes?
Answer: 900