It is not obvious on the 1040, but the Tax on line 11 is not always calculated using the Tax Tables on the Taxable Income in line 10.
The most common case is when the Taxable Income on line 10 includes capital gains or qualified dividends. In this case, a separate worksheet is created that shows the ordinary income (less the capital gains and qualified dividends) taxed at the regular rates and capital gains/qualified dividends taxed at the lower capital gains rate. These two tax results are then added together and placed in line 11.
Thus, the Tax seen on line 11 will not appear to match a simple tax calculation on the whole Taxable Income amount in line 10.
