Six days. The interest on reverse repurchase of treasury bonds is calculated according to the number of days actually occupied by funds. Buy 7-day treasury bonds for reverse repurchase on Friday, and the actual interest-bearing days are 6 days. The specific calculation method of interest is: the interest is equal to the principal multiplied by the interest rate multiplied by the number of days of 365 minutes, where the principal refers to the amount of reverse repurchase of government bonds purchased by investors, the interest rate refers to the annualized rate of return of reverse repurchase of government bonds, and the number of days refers to the calendar days actually occupied by funds, excluding holidays and weekends.