How many ways can you make 45 cents using less than 21 coins?

To determine the number of ways to make 45 cents using less than 21 coins, we can use a combination of different denominations: pennies (1 cent), nickels (5 cents), dimes (10 cents), and quarters (25 cents). The specific combinations depend on the constraints of the number of coins and their values. A systematic approach or dynamic programming can be employed to calculate the exact number of combinations while ensuring the total number of coins remains below 21. The exact number of combinations can be determined through computational methods or combinatorial analysis.