On January 10, 2012, Montgomery Corporation purchased machinery that cost $750,000. The entire cost was recorded as an expense. The machinery has an estimated useful life of 10 years and a $30,000 salvage value. Montgomery uses the straight-line method to account for depreciation expense. The error was discovered on December 29, 2013. Ignore income tax considerations. Montgomery's income statement for the year ended December 31, 2013, should show the cumulative effect of this error in the amount of:
a) $648,000
b) $576,000
c) $504,000
d) $-0-