Net debt is calculated as total financial liabilities (non‑current plus current financial liabilities) less cash and cash equivalents.  
- Total financial liabilities at end‑2022 = 5 543 755 000 € + 1 705 277 000 € = 7 249 032 000 €  
- Cash and cash equivalents at end‑2022 = 794 824 000 €  
- Net debt = 7 249 032 000 € – 794 824 000 € = 6 454 208 000 €  

EBITDA is operating profit plus depreciation and amortisation:  
- Operating profit (profit from operating activities) = 961 554 000 €  
- Depreciation and amortisation = 544 992 000 €  
- EBITDA = 961 554 000 € + 544 992 000 € = 1 506 546 000 €  

Net debt / EBITDA = 6 454 208 000 € / 1 506 546 000 € ≈ 4.28  

<answer>4.28</answer>