These totals are then divided by the number of constituency seats each party has won - plus one.

The party with the highest resulting total elects one Additional Member. That party's divisor is then increased by one (for its victory) and new figures calculated. Again, the party with the highest total wins a seat.

The process is then repeated until all seven Additional Members are elected.

Here is an example of how the seven Additional Members might be elected to the Scottish Parliament from the Lothians region.

It uses the voting figures from the 1997 general election and for the sake of simplicity assumes that people cast their party list ballots for the same party or individual as they did for their constituency vote.

Lothians - 1997 general election result

			Con		Lab		LD		SNP		Others
	Votes		73,363		175,354		56,957		70,353		5,719
	Shares %		19.2		45.9		14.9		18.4		1.5
	Constituency Seats		0		8		1		0		0

For the sake of presentation, Others have been omitted from the following example, but it must be emphasised that the Additional Member System generally assists the election of small parties.

First Round

As you can see below, Labour has polled the highest number of votes, but its divisor is very high (8 + 1 = 9) because it has won most of the constituency seats in the Lothian region.

With 73,363, the Conservatives have the highest total after dividing, just ahead of the SNP's 70,353, so they win the first Additional Member.

Click here for the second round

Con

Lab

LD

SNP

Elected

Total votes

73,363

175,354

56,957

70,353

Constituency seats won

0

8

1

0

1st divisor

0 + 1 =1

8 + 1 =9

1 + 1 = 2

0 + 1 = 1

1st total

73,363

19,484

28,479

70,353

Con

2nd divisor

2nd total

3rd divisor

3rd total

4th divisor

4th total

5th divisor

5th total

6th divisor

6th total

7th divisor

7th total