For instance, Web browsers generally bring HTML code into the system via port 80, while FTP programs transfer files through port 21.

CNN: Symantec offers Web-based PC checkups

Guernsey's lifeboat in St Peter Port dealt with 21 call outs, while Alderney's lifeboat launched 24 times.

BBC: RNLI's 'busiest' year for SW flood rescues

Rage exploded again when a judge sentenced to death 21 residents of Port Said for their roles in a deadly soccer riot last year.

CNN: Could Egypt fall apart?

One aggrieved investor recounts how his firm had to wait months to get approval to take over a port terminal, because it needed 21 separate entities to sign off.

ECONOMIST: Investing in Brazil��s infrastructure

Mr Morsi declared a state of emergency in Port Said, Suez and Ismailia, and a 21:00 to 06:00 curfew from Monday.

BBC: Egypt's Morsi calls crisis talks as emergency declared

Port Said has been rocked by violence since January, when 21 local football fans were sentenced to death over deadly football riots in 2012.

BBC: Five killed in Egyptian clashes

Of the 42 police officers working the morning shift at Kennedy Airport on Friday, for example, 21 were paid through overtime, according to the Port Authority Police Benevolent Association, the officers' union.

WSJ: Port Authority Spends More on Overtime

Incidents began on 18 March with 21 grass fires in Carmarthenshire, four in Ceredigion, 42 in Neath Port Talbot, 24 in Pembrokeshire, 26 in Powys and 69 in Swansea.

BBC: Grass fire threat to overhead wires near Pontycymer