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graup/decimal.py

Created January 10, 2017 16:56
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The reason why you should be careful with currency amount calculation
Raw
decimal.py
>>> from decimal import *
>>> VAT_RATE = Decimal('0.19')
>>> amount = Decimal('12.12')
>>> ((amount / (VAT_RATE + 1)).quantize(Decimal('1.00')) * (1+VAT_RATE)).quantize(Decimal('1.00'))
Decimal('12.11')
>>> ((amount / (VAT_RATE + 1)).quantize(Decimal('1.0000')) * (1+VAT_RATE)).quantize(Decimal('1.00'))
Decimal('12.12')
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