What's the ideal number of friends?

The more friends you have, the more you earn, says a study. But modern life can allow little time to maintain meaningful relationships, so what's the optimum number of friends?

It's widely accepted that friendships are invaluable to the soul but few of us were aware that they could also boost the bank account.

A study of 10,000 US students over a period of 35 years suggests the wealthiest people are those that had the most friends at school. Each extra schoolfriend added 2% to the salary.

The researchers said this was because the workplace is a social setting and those with the best social skills prosper in management and teamwork.

If a wide circle of friends is taken as a popularity indicator, does that mean the more you have the more successful and happy you are? Or can you have too many? What is the best number?

The average number is about 150, says leading anthropologist Robin Dunbar.