You do not specify a country, but most countries change the design of their bank notes periodically to make it a little more difficult for counterfeiters.
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You do not specify a country. The first Australian One Hundred Dollar note was issued well after Australia's changeover to decimal currency in 1984. The first New Zealand One Hundred Dollar note was issued at New Zealands changeover to decimal currency in 1967.
The New Zealand Twenty Dollar note issued from 1967 to 1991 was 160 x 80 mm. The New Zealand Twenty Dollar note issued from 1992 to present is 145 x 70 mm.
The New Zealand One Hundred Dollar note was first issued in 1967 when the currency was changed from Pounds to Dollars.
The original paper Fifty Dollar note released between 1973 and 1993, had Lord Howard Walter Florey (Pathologist) on the front, and Sir Ian Clunies Ross (Veterinary scientist) on the back. They were progressively withdrawn from circulation in favour of the polymer notes from 1995. The new polymer Fifty Dollar note released from 1995 onwards, has David Unaipon (Inventor, preacher & author) on the front, and Dame Edith Cowan (Social worker, politician & feminist) on the back.
The current New Zealand Five Dollar note features Sir Edmund Hillary. The current New Zealand Ten Dollar note features Kate Sheppard. The current New Zealand Fifty Dollar note features Sir Apirana Ngata. The current New Zealand One Hundred Dollar note features Lord Ernest Rutherford.
The current New Zealand Five Dollar note issued from 1992, features Sir Edmund Hillary (mountaineer, explorer and philanthropist) on the obverse. The current New Zealand Ten Dollar note issued from 1993, features Kate Sheppard (women's suffrage) on the obverse. The current New Zealand Twenty Dollar note issued from 1999, features Queen Elizabeth II. The current New Zealand Fifty Dollar note issued from 1992, features Sir Apirana Ngata (politician) on the obverse. The current New Zealand One Hundred Dollar note issued from 1999, features Lord Ernest Rutherford of Nelson (the Father of the Atom) on the obverse.
Sir Edmund Hillary with Mount Everest is depicted on the New Zealand $5 note issued from 1992.
All of New Zealands circulating banknotes are made from a polymer compound. The Five, Ten, Twenty and One Hundred Dollar polymer notes were first issued in 1999. The Fifty Dollar polymer notes were first issued in 2000.
The new polymer notes are mostly gold but have a few patches of green and red as well.
There are serial numbers on all New Zealand banknotes. The serial number helps to track the note and makes counterfeiting that little more difficult.
An Australian 1995 Fifty Dollar note, uncirculated and in absolute mint condition could fetch up to $275 AUD. If it has circulated but still in good condition, it might fetch up to $135 AUD. If it is the first or last of a serial number range, or a Star note, the value will increase dramatically. 1995 was the first release of the new polymer Australian Fifty Dollar note. A reputable coin dealer will be able to give a more accurate valuation.