First Lady Michelle Obama greets members of the general public as they enter the Blue Room during their White House tour, Feb. 16, 2012. Chuck Kennedy/The White House

ABC News tried all day yesterday to get an answer out of the White House and Secret Service about how much money will be saved by canceling White House tours. Now we have an answer: $74,000 per week, according to Secret Service spokesman Ed Donovan.

Here's how they do the math:

The Secret Service says it takes an average of 37 officers to secure the tours. Each officer's total pay (including benefits) averages $50 an hour. And, although the tours only are only open for 20 ½ hours per week, Donovan says the officers are on the clock for 40 hours. So - 37 officers at $50 an hour for 40 hours a week adds up to $74,000.

SEE VIDEO: White House ending tours

It's not entirely clear, however, how shutting the tours saves the entire sum of money: All of those officers will continue to be paid, with benefits. The Secret Service plans no furloughs. The officers will be reassigned to other posts, though, cutting the need for overtime.

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