Question: How many islands are in the chain where the currently-used currency came into existence in 1965 ?

text: Currency union
List of currency unions -- Existing

A currency union (also known as monetary union) is an intergovernmental agreement that involves two or more states sharing the same currency. These states may not necessarily have any further integration (such as an economic and monetary union, which would have, in addition, a customs union and a single market). There are three types of currency unions:
Currency Users Est Status Population
CFA franc Benin Burkina Faso Côte d'Ivoire Guinea-Bissau Mali Niger Senegal Togo Cameroon Central African Republic Chad Republic of the Congo Equatorial Guinea Gabon 1945 Formal , common policy 151,978,440
CFP franc French Polynesia New Caledonia Wallis and Futuna 1945 Formal , common policy 552,537
Eastern Caribbean dollar Anguilla Antigua and Barbuda Dominica Grenada Montserrat Saint Kitts and Nevis Saint Lucia Saint Vincent and the Grenadines 1965 Formal , common policy de facto EMU for CSME members 625,000
Euro Eurozone : Austria Belgium Cyprus Estonia Finland France Germany Greece Ireland Italy Latvia Lithuania Luxembourg Malta Netherlands Portugal Slovakia Slovenia Spain and EU special territories : Akrotiri and Dhekelia ( SBAs ) French Southern and Antarctic Lands Saint Barthélemy Saint Martin Saint Pierre and Miquelon Andorra Kosovo Monaco Montenegro San Marino Vatican City 1999/2002 Formal , common policy and EMU for EU members Formal for Monaco and SBAs ( those form a de facto EMU with the Eurozone ) Formal for Andorra since 2011 Informal for Kosovo , Montenegro Formal for the rest 341,008,867
Hong Kong dollar Hong Kong Macau 1977 Informal ; Decreto-Lei n.º 16/95/M prohibiting the refusal of the pataca by merchants and businesses 7,775,200
Singapore dollar Brunei dollar Brunei Singapore 1967 Formal ; currencies mutually exchangeable 5,137,000
Australian dollar Australia and external territories : Ashmore and Cartier Islands Australian Antarctic Territory Christmas Island Cocos ( Keeling ) Islands Coral Sea Islands Heard Island and McDonald Islands Norfolk Island Kiribati Nauru Tuvalu 1966 Informal 24,557,000
Pound sterling United Kingdom and overseas territories : British Antarctic Territory British Indian Ocean Territory Falkland Islands Gibraltar Saint Helena , Ascension and Tristan da Cunha South Georgia and the South Sandwich Islands and crown dependencies : Guernsey Isle of Man Jersey 1939 Semi-formal . UK banknotes are legal tender in locations outside the UK . Local currencies are pegged to the GBP but not necessarily accepted in the UK : Guernsey pound , Manx pound , Jersey pound and Alderney pound , Falkland Islands pound , Gibraltar pound , Saint Helena pound 62,321,000
Indian rupee India Bhutan Nepal 1974 Informal Nepal minor usage 1,352,000,000
New Zealand dollar New Zealand and realm : Cook Islands Niue Pitcairn Islands 1967 Informal 4,411,000
Israeli new sheqel Israel Palestine 1927/1986 Informal 11,738,000
Jordanian dinar Jordan Palestine ( West Bank only )  Informal 8,922,000
Russian ruble Russia Abkhazia South Ossetia 2008 Informal 142,177,000
South African rand Lesotho Namibia South Africa Eswatini 1974 Formal de facto customs and monetary union for SACU members 52,924,669
Swiss franc Liechtenstein Switzerland 1920 Informal de facto economic and monetary union - 1924 creation of a customs union , then members of the European Free Trade Association ( a common market ) , and now also part of the European Single Market 8,547,015
Turkish lira Turkey Turkish Republic of Northern Cyprus 1983 Informal 75,081,100
United States dollar United States and insular areas : American Samoa Guam United States Minor Outlying Islands Northern Mariana Islands Puerto Rico United States Virgin Islands Ecuador El Salvador Panama Marshall Islands Federated States of Micronesia Palau Timor-Leste Turks and Caicos Islands British Virgin Islands BES islands 1904 ( Panama only ) Formal for insular areas and sovereign status with Compact of Free Association , informal for other areas 339,300,000