Four pairs of political parties have signed vote-sharing agreements with each other, which may enable one of each pair to benefit from the "surplus" votes that each of them receives, the Central Election Committee announced on Sunday. The pairs consist of the Labor-Meimad Party and Meretz, Shas and UTJ, Hadash and Balad, and Israel Beiteinu and the Likud. According to the 1969 Knesset Elections Law, the system of determining the allocation of parliamentary seats is as follows. The total number of proper votes cast in the elections is divided by 120 - the number of seats in the Knesset - to determine exactly how many votes are required to win one seat. A party must win exactly that number of votes for each parliamentary seat allotted to it. Political parties who do not sign vote-sharing agreements lose any surplus votes. However, parties who have reached vote-sharing agreements place their surplus votes into a joint kitty. If the sum total of the surplus votes of the two parties is enough to win another parliamentary seat, one of the two will win it. In order to decide which one, each party's total number of votes received is divided by the number of parliamentary seats that party has won. The result is called the "index." The party with the larger index of the two wins the extra seat. In general, the parties who sign vote-sharing agreements are usually the largest ones. They pair off with parties who are ideologically close to them so that the party with the smaller index will still gain something out of the fact that a party with a similar political outlook has won an additional representative, partly thanks to its votes.