On modern devices, the unlock partition is AES-256 encrypted with a unique hardware-backed key (TEE - Trusted Execution Environment). No calculator can break this; you must contact Huawei customer service, use the "Find Device" cloud service, or perform a full reflash with a bootloader unlock (which Huawei banned in 2018 for most markets).
Modern Huawei devices use advanced algorithms (often referred to as "New Algo" v3, v4, or v5) that tie the unlock code directly to the device's unique number. Because these algorithms are complex, specialized "calculators" are used to derive the 16-digit key from the 15-digit IMEI. How to Get Your 16-Digit Unlock Code Huawei Code Calculator 16 Digit