Will the GOP win the 39 seats they need to take control of the House? How about the 10 Senate seats they need for a majority? Here's a by-the-numbers survey of predictions for how the elections will turn out, how much they will cost, and who will participate:

Current Democratic majority in the 435-seat House of Representatives

Number of vulnerable Democrat-held House seats (National Review's Jim Geraghty)

Number of vulnerable Republican-held House seats (FiveThirtyEight)

7 in 8
Chances that the Republicans take control the House (Intrade)

Estimated number of House seats the GOP will win (Republican pollster Bill McInturff, NBC/WSJ)

Majority that would give the GOP

1 in 3
Chances that Republicans will take control of the Senate (Intrade)

Projected number of Senate seats the GOP will win, for a post-election total of 48 seats (FiveThirtyEight)

Probability that Senate Majority Leader Harry Reid (D-NV) will keep his job (Intrade)

$564 million
Total amount that will be spent in 2010 by outside political committees and nonprofits (Campaign Finance Institute)

Percentage increase in spending that would mark over 2008

$189 million
Amount spent so far by Super-PACs, unions, and nonprofits (Sunlight Foundation)

$97.5 million
Amount of that money from undisclosed donors

$140 million
Estimated spending by Meg Whitman (R) in her California gubernatorial bid — a record for a non-presidential campaign

Predicted voter turnout nationwide (Gallup)

Percentage of likely voters in 92 key districts who support the Tea Party (NBC/Wall Street Journal)

Percent of likely Democratic voters in 92 key districts very interested in the election (NBC/WSJ)

Percent of likely Republican voters in 92 key districts very interested in the election (NBC/WSJ)