more details needed... does it feed a transformer? is it direct from mains?is is it rated for 230V? is it class 1 or 2 (1: need earth, 2: double insulated, no earth)?
got a photo? unless its really crappy it sounds like you may be dealing with a wall wart type power adaptor which you can't just cut off and replace with a plug.
If you post me the core colours I will tell you which goes where.
Just for the information of others here, Russia and the entire former Soviet States all use 230V 50Hz ac supplies.
Many of the installations do not have an Earth connection and thus there is unlikely to be a requirement for one in the calculator, it is likely to be double insulated and the transformer in the Unit will be of the Isolating type.
Usually Russian equipment will have Red and Black cores, with Red being live and Black Neutral, however the Transformer will be a basic affaior so if the cores where connected in reverse the unit would still work and the suffer no ill consequences as a result.
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