Question 696945
10% of the original cost is {{{ .1*2.7 = .27 }}} million dollars
The sum of the costs of buildings 1 through 10,000 is
 1st building = {{{ 2.7 }}}
2nd building = {{{ 2.7 + .27 }}}
3rd building = {{{ 2.7 + 2*.27 }}}
4th building = {{{ 2.7 + 3*.27 }}}
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Sum = {{{ 10000*2.7 }}} + ( 1 + 2 + 3 + 4 + . . .  + 10000 )*.27 
The second part of this is {{{ (( 10000*10001) / 2)*.27 }}}
{{{ (( 10000*10001) / 2)*.27 }}}
{{{ ( 100010000/2) * .27 }}}
{{{ 50.005000*.27 }}}
{{{ 13501350 }}}
Finishing the sum:
{{{ 27000  + 13501350 = 13528350 }}}
The cost altogether is
$ 13,528,350 million dollars
or 13 trillion, 528 billion, 350 million dollars
( unless I messed this up )