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Validating Improved Payoff Formula
Formula: Total Payoff = P + (P × R/365 × D)
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=== Test Case 1: Manual Verification ===
Principal: 1,000,000.00
Annual Rate: 12%
Days: 30
Daily Rate: 0.000328767
Interest: 9,863.01
Total Payoff: 1,009,863.01

Validation:
Interest calculation: ✓ PASS
Payoff calculation: ✓ PASS

=== Test Case 2: Amortization Verification ===
Loan Amount: 1,000,000.00
Monthly Rate: 1%
Tenure: 12 months
Monthly Payment: 88,848.79

Amortization Schedule:
Month | Interest | Principal | Balance
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    1 | 10000.00 |  78848.79 |  921151.21 ✓
    2 |  9211.51 |  79637.28 |  841513.93 ✓
    3 |  8415.14 |  80433.65 |  761080.29 ✓

Validation: ✓ PASS

=== Test Case 3: URL013572 Loan Verification ===
Requested Amount: 6,397,076.00
Monthly Payment: 177,697.00
Tenure: 36 months
Installments Paid: 5
Calculated Original Principal: 5,350,013.32

Outstanding Principal after 5 payments: 4,716,484.48
Pro-rated Interest (7 days): 10,854.38
Total Payoff: 4,727,338.86

Validation:
Original Principal: ✓ PASS
Outstanding Principal: ✓ PASS
Pro-rated Interest: ✓ PASS
Total Payoff: ✓ PASS

=== Test Case 4: Edge Cases ===
Test: Zero Interest Rate
  Interest: 0.00 (expected: 0.00) ✓
  Payoff: 100,000.00 (expected: 100,000.00) ✓
Test: One Day Interest
  Interest: 32.88 (expected: 32.88) ✓
  Payoff: 100,032.88 (expected: 100,032.88) ✓
Test: Full Year Interest
  Interest: 12,000.00 (expected: 12,000.00) ✓
  Payoff: 112,000.00 (expected: 112,000.00) ✓

Validation: ✓ PASS

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Test Summary
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Total Tests: 4
Passed: 4
Failed: 0

✓ All tests PASSED! The improved formula is working correctly.
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