Mind Games: The numbers Gaelic football referees are required to master

Stephen O'Brien, Barry O'Sullivan, Ryan Wylie and Ger Egan are just four inter-county footballers who claim the new experimental rules will be a burden on referees.

If it's not measuring the 20 metres that must be kicked from outside the opposition's 45-metre line to inside it, it's keeping count of three consecutive handpasses, a process that restarts over and over, while ensuring no fouls are being committed, maybe administering the five-second advantage rule and keeping an eye on other areas of the field.

Taking the players' lead, we’ve listed just some of the maths an inter-county referee must do in and around officiating a game and it's exhaustive. The arithmetic and geometry may be basic for the most part.

Nevertheless, it is relentless...

0 Players sent off in normal time can play in extra-time.

0 yellow cards carry over in extra-time.

1 Hop permitted upon receiving ball in open play. The ball must be soloed before it can be hopped again.

1 yellow and one black card makes ared card.

1 black card following a sin-bin and a yellow card converts to a red card.

1 black card following a sin-bin black card translates to a red card.

1 A fisted point attempt is allowed on the fourth hand-pass.

2 Ticks constitutes a yellow card.

2 Yellow cards equal a red card.

2 A second foul during an advantage period by either team supersedes the first one and results in a free.

3 Consecutive hand-passes is the current limit.

3 Black cards before a team can no longer replace offending players (includes extra-time).

3 Substitutes allowed per team in extra-time.

4 Steps allowed in possession before ball must be hopped or soloed.

4 Steps is the number aplayer who has claimed a kick-out mark can’t be interfered with by an opponent (doesn’t apply to offensive/defensive mark).

5 Second Advantage Rule.

5Substitutes (having returned from six).

5 Seconds aplayer is permitted to kick a kick-out mark.

6 Players per team in their attacking half of field at start of each half.

7 Players per team in their defending half of field at start of each half.

10 Minutes is the length of the sin-bin, which doesn’t consider stoppages.

11 Maximum of available substitutes to choose from.

13 Metres minimum distance for a kick-out.

13 Metres is the distance an opponent can’t interfere with the kick of a player who has after taking a kick-out mark.

13 Metres an opposing player must be away from an opponent taking a free/sideline.

13 Metre free for a late foul and the ball has landed over the end-line.

13 Metres the ball is brought forward for dissent.

15 Minute half-time interval.

15 Players per team at the start of extra-time irrespective of red cards in normal time.

15 Seconds is the time permitted for a free to be taken after an offensive/defensive mark has been awarded.

20 Metres a ball must travel from outside the 45m line for an offensive/defensive mark to be taken inside that line.

20 Metre-line within which no attacking player can be for a kick-out.

20 Metre-line on or within sideline kicks don't have to be kicked forward.

20 Seconds to include as additional time per single/double/triple substitute.

24 Hours, time in which areportmust be submitted.

26 Maximum number jersey for a player. Anything more, other than for a blood sub injury, is deemed a fining offence.

30 Gumshields must be worn on the field of play.

35 Minutes per half/30 in club football.

45 Metre lines between which akick-out mark can be awarded.