The calculation formula of annualized income is: annualized income = principal × annualized rate of return. When the principal is 1 ten thousand yuan and the annualized interest rate is 4.5%, the annualized income = 1 ten thousand× 4.5% = 450 yuan, and the monthly interest is 450/ 12 = 37.5 yuan. It should be noted that the annualized rate of return is calculated by converting the current rate of return (daily rate of return, weekly rate of return and monthly rate of return) into annualized rate of return, which is a theoretical rate of return, not an actual rate of return.