inflation rate

what is inflation rate?In ecnomics, the inflation rate is a measure of inflation, the rate of increase of a price index like CPI that means consumer price index. The rate of decrease in the purchasing power of money is approximately equal.in Britain government announce the CPI everymonth ,and the inflation rate is the the perventage of CPI increase over the 12 monthes.
And also it's used to calculate the real interest rate,what is real interest rate? it means approximately the nominal (名义上的) the interestn rate minus the inflation rate as well as real increases in wages, and official measurements of this rate act as input variables to COLA adjustments and Inflation derivatives prices.excipt thw consumer price index,there are other ways can know the inflation rates,for instance, you can announced product price index,food price index,and the house price index,export price index.and you need think about tax price index and etc. there are have different inflation.,because of the percentage increase by year. Also ,it can depends on the rate of wages. the fomular of inflation rate is inflaton rate = (Pt-Pt-1/Pt-1)×10%