LONDON - Britons take to the polls on Thursday to elect a parliament and a government for the next five years.

Here are a few key numbers in the election:

326: The clear majority in the 650-seat parliament that the two main parties - Conservatives and Labour - are aiming for and look unlikely to reach on their own.

Only the speaker of the outgoing parliament, John Bercow, is guaranteed re-election as none of the main parties are putting candidates against him.

In reality, the magic number could be slightly lower than 326 as Irish nationalists Sinn Fein refuse to take up their seats in the House of Commons.

37 days: The length of the official campaign, which was formally launched on March 30 after the dissolution of parliament. It has been the longest campaign in Britain's modern political history - although far shorter than campaigns in, for example, the United States.

81: The number of opinion polls published during the campaign until Tuesday ahead of the knife-edge vote.

30: Polls that put the centre-right Conservative Party ahead.

37: Polls that put centre-left Labour Party ahead.

3,971: The number of candidates in the election - 162 fewer than in 2010 when there were 4,133.

26.1 percent: The proportion of female candidates - higher than the 21.1 percent recorded in 2010. The Green Party has the highest share of women - 37 percent of its candidates - and the anti-EU UK Independence Party the lowest at 12 percent.

The outgoing House of Commons had 143 female MPs.

72: The number of fringe and single-issue parties that are putting forward just a single candidate.

485,012: The number of people who registered to vote on April 20, the day the deadline expired. Some two million voters registered between mid-March and April 20 in a country where abstention rates were at 35 percent in elections in 2010 and 38 percent in 2005.

15 percent: The proportion of voters who have already cast postal ballots.

4,658,499: The amount in pounds (6.30 million euros, $7.10 million) raised by Labour during the election campaign. The Conservatives raised £3.45 million, UKIP £1.61 million and the Liberal Democrats £234,000.

18.3 million: The cumulative number of viewers of different debates and interviews with the main candidates broadcast on British television.