According to the United States Treasury Department, the U. S. national debt was 1.815\times 10^{13}1.815×10 13 dollars on September 30, 2015. On September 29, 2005, the national debt was 4.974\times 10^{12}4.974×10 12 dollars. Find the amount of increase in the national debt from September of 2005 to September of 2015. Write a sentence describing the increase in the national debt from 2005 to 2015 using scientific notation and using standard form.