It just adds up — every vote counts

MATHEMATICAL analysis of historical data reveals a simple rule of thumb to predict the number of seats that a big party may win in a general election.

Take the national percentage figure of first-preference votes for a big party as a number between 0 and 100 — double it, round the answer and subtract five.

The most recent opinion poll shows Fine Gael surging ahead at 35%. Support for the Labour Party is stabilising at 21%. Fianna Fáil and Sinn Féin each languish at 14%. The total number of seats up for grabs is 165.