=== Testing Actual Reducing Balance Formula ===

Test Case 1: URL013572 (CHIBITA Import)
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Principal: 6,397,076.00
Annual Rate: 12%
Tenure: 36 months
Installments Paid: 5
Calculated Monthly Payment: 212,474.46
Remaining Balance (Payoff): 5,639,557.86
Expected from logs: 3,774,876.79

Actual Monthly Payment from Import: 177,697.00
Payoff with Actual Payment: 4,716,484.48

Test Case 2: URL002224 (From Error Log)
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Principal: 18,980,000.00
Annual Rate: 12%
Tenure: 49 months
Installments Paid: 15
Calculated Monthly Payment: 491,861.75
Remaining Balance (Payoff): 14,117,743.53

Test Case 3: Simple Verification
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Principal: 1,000,000.00
Annual Rate: 12%
Tenure: 12 months
Installments Paid: 3
Calculated Monthly Payment: 88,848.79
Remaining Balance (Payoff): 761,080.29
Remaining Payments: 9
Monthly Payment × Remaining: 799,639.10 (if no interest)

=== Formula Summary ===
The actual reducing balance formula calculates:
1. Monthly Payment = P × [r(1+r)^n] / [(1+r)^n - 1]
2. Remaining Balance = Monthly Payment × [1 - (1+r)^(-remaining)] / r
Where: P = Principal, r = Monthly Rate, n = Total Tenure