It may be her official residence, but the Queen couldn't afford to buy Buckingham Palace if it was up for sale without getting a mortgage.

With her net worth estimated to be £405,484,450 (that's just over £4 million) she's not exactly strapped for cash - but still, she'd be £4 billion short if she wanted to own the palace outright.

Based on research by property valuation experts at Emoov, Buckingham Palace's selling price is estimated to be £4.9bn - with a square metre costing £64,8311.

If sold, Buckingham Palace could make up 0.2 per cent of the UK’s GDP. Eek.

This makes it by far the most expensive official home of any world leader, with 10 Downing Street valued at £61,871,653 and even the White House costing a fraction of the price at £396,868,657.

With so many digits, we can barely understand it!

Put it this way - the average price per square metre in Central London is £11,523 - Buckingham Palace is 5,000 per cent more.

The monthly mortgage payment was estimated to be £22,530,176, which is 8,072 times the average monthly salary in London - £2,790.765.