Federal debt was 17.3 trillion in 2014 and 13561623 (in millions) in 2010. how much more was the federal debt in 2014 compared to 2010?

We have that
In 2014 --->  the federal debt was 17.3 trillion
n 2010> the federal debt was 13,561,623 millions

we know that
one trillion> 1,000,000,000,000> 1 x 10^12
so
17.3 trillion> 17.3 x 10^12> 1.73 x 10^13
[1.73 x 10^13-13,561,623]=17,300,000,000,000-13,561,623]
=17,299,986,438,377

the answer is
17,299,986,438,377

Maybe the answer is 20mm. all i really did was just multiply, which is obvious.