This is found by using the cost of the work estimate given in the architect’s memo, which is $19,500,000. We need to find the cost per square foot, so divide the total cost by the number of square feet given in the memo, which is 52,000 square feet:

$19,500,000 / 52,000 sf = $375/sf

If we increase the square footage by 10%, we get:

1.10 * 52,000 sf = 57,200 sf

We then multiply that by the cost per square foot we just found:

57,200 sf * $375/sf = $21,450,000

And add on the extra $15,000 for the finish change:

$21,450,000 + $15,000 = $21,465,000

ERROR 10%=.01 NOT 1.10