Explain about the nominal Gross domestic product

It isn't very common to use CPI in construction of real GDP. The reason is that CPI measures the price evolution of consumer goods whereas GDP includes investment goods and consumer goods. Rather, it is common to use a GDP deflator as a price index. GDP deflator measures the price evolution of a basket whose composition is close to composition of GDP. Difference between the GDP deflator and the CPI is fairly small however. To avoid confusion, GDP that is not adjusted for inflation is often called nominal GDP.