The CUMIPMT function in Excel calculates the cumulative interest paid on a loan between two periods. In simple terms, this function helps you determine how much interest has been paid on a loan during a specific period, based on the loan's interest rate, payment schedule, and loan amount. This function is especially useful in loan amortization schedules and financial modeling.

The COUPPCD function in Excel returns the previous coupon date before the settlement date of a bond. In other words, it helps you determine the last interest payment date that occurred before you purchased the bond. This function is useful for accrued interest calculations, bond pricing, and financial reporting.

The COUPNUM function in Excel calculates the number of coupon periods between the settlement date and the maturity date of a bond. In simple words, it tells you how many interest payments are left for the bond from the purchase date until it matures. This function is very useful for bond investment analysis, amortization schedules, and pricing bonds.