what is the 2011 total interest expense in billions based on the weighted-average debt level and effective interest rate?
Important information:
text_1: interest expense 2013 interest expense decreased in 2012 versus 2011 reflecting a lower effective interest rate in 2012 of 6.0% ( 6.0 % ) versus 6.2% ( 6.2 % ) in 2011 as the debt level did not materially change in 2012 .
text_2: interest expense decreased in 2011 versus 2010 due to a lower weighted-average debt level of $ 9.2 billion versus $ 9.7 billion .
text_3: the effective interest rate was 6.2% ( 6.2 % ) in both 2011 and 2010 .
Reasoning Steps:
Step: multiply1-1(9.2, 6.2%) = .570
Program:
multiply(9.2, 6.2%)
Program (Nested):
multiply(9.2, 6.2%)

Please answer the following financial question based on the context provided. Make sure to give the answer in raw number, not in percentage and without any units. If the question asks for percentage the value should be less than 1
Context:
other income increased in 2011 versus 2010 due to higher gains from real estate sales , lower environmental costs associated with non-operating properties and the comparative impact of premiums paid for early redemption of long-term debt in the first quarter of 2010 . interest expense 2013 interest expense decreased in 2012 versus 2011 reflecting a lower effective interest rate in 2012 of 6.0% ( 6.0 % ) versus 6.2% ( 6.2 % ) in 2011 as the debt level did not materially change in 2012 . interest expense decreased in 2011 versus 2010 due to a lower weighted-average debt level of $ 9.2 billion versus $ 9.7 billion . the effective interest rate was 6.2% ( 6.2 % ) in both 2011 and 2010 . income taxes 2013 higher pre-tax income increased income taxes in 2012 compared to 2011 . our effective tax rate for 2012 was relatively flat at 37.6% ( 37.6 % ) compared to 37.5% ( 37.5 % ) in 2011 . income taxes were higher in 2011 compared to 2010 , primarily driven by higher pre-tax income . our effective tax rate remained relatively flat at 37.5% ( 37.5 % ) in 2011 compared to 37.3% ( 37.3 % ) in 2010 . other operating/performance and financial statistics we report key performance measures weekly to the association of american railroads ( aar ) , including carloads , average daily inventory of freight cars on our system , average train speed , and average terminal dwell time . we provide this data on our website at www.up.com/investors/reports/index.shtml . operating/performance statistics railroad performance measures reported to the aar , as well as other performance measures , are included in the table below : 2012 2011 2010 % (  % ) change 2012 v 2011 % (  % ) change 2011 v 2010 .
Table
                                         | 2012  | 2011  | 2010  | % (  % ) change 2012 v 2011 | % (  % ) change 2011 v 2010
average train speed ( miles per hour )   | 26.5  | 25.6  | 26.2  | 4 % (  % )                  | ( 2 ) % (  % )             
average terminal dwell time ( hours )    | 26.2  | 26.2  | 25.4  | - % (  % )                  | 3 % (  % )                 
average rail car inventory ( thousands ) | 269.1 | 272.9 | 274.4 | ( 1 ) % (  % )              | ( 1 ) % (  % )             
gross ton-miles ( billions )             | 959.3 | 978.2 | 931.4 | ( 2 ) % (  % )              | 5 % (  % )                 
revenue ton-miles ( billions )           | 521.1 | 544.4 | 520.4 | ( 4 ) % (  % )              | 5 % (  % )                 
operating ratio                          | 67.8  | 70.7  | 70.6  | ( 2.9 ) pts                 | 0.1 pts                    
employees ( average )                    | 45928 | 44861 | 42884 | 2 % (  % )                  | 5 % (  % )                 
customer satisfaction index              | 93    | 92    | 89    | 1 pt                        | 3 pts                      
average train speed 2013 average train speed is calculated by dividing train miles by hours operated on our main lines between terminals . average train speed , as reported to the association of american railroads ( aar ) , increased 4% ( 4 % ) in 2012 versus 2011 . efficient operations and relatively mild weather conditions during the year compared favorably to 2011 , during which severe winter weather , flooding , and extreme heat and drought affected various parts of our network . we continued operating a fluid and efficient network while handling essentially the same volume and adjusting operations to accommodate increased capital project work on our network compared to 2011 . the extreme weather challenges in addition to increased carloadings and traffic mix changes , led to a 2% ( 2 % ) decrease in average train speed in 2011 compared to 2010 . average terminal dwell time 2013 average terminal dwell time is the average time that a rail car spends at our terminals . lower average terminal dwell time improves asset utilization and service . average terminal dwell time remained flat in 2012 compared to 2011 , despite a shift in traffic mix to more manifest shipments , which require more switching at terminals . average terminal dwell time increased 3% ( 3 % ) in 2011 compared to 2010 . additional volume , weather challenges , track replacement programs , and a shift of traffic mix to more manifest shipments , which require additional terminal processing , all contributed to the increase . average rail car inventory 2013 average rail car inventory is the daily average number of rail cars on our lines , including rail cars in storage . lower average rail car inventory reduces congestion in our yards and sidings , which increases train speed , reduces average terminal dwell time , and improves rail car utilization . despite a shift in traffic mix from coal to shale-related and automotive shipments with longer .
Question: 
what is the 2011 total interest expense in billions based on the weighted-average debt level and effective interest rate?
Important information:
text_1: interest expense 2013 interest expense decreased in 2012 versus 2011 reflecting a lower effective interest rate in 2012 of 6.0% ( 6.0 % ) versus 6.2% ( 6.2 % ) in 2011 as the debt level did not materially change in 2012 .
text_2: interest expense decreased in 2011 versus 2010 due to a lower weighted-average debt level of $ 9.2 billion versus $ 9.7 billion .
text_3: the effective interest rate was 6.2% ( 6.2 % ) in both 2011 and 2010 .
Reasoning Steps:
Step: multiply1-1(9.2, 6.2%) = .570
Program:
multiply(9.2, 6.2%)
Program (Nested):
multiply(9.2, 6.2%)
