I wrote and it get compiled successfully but when I used qemu to test it and get incohrent numbers enter image description here

    static UINT64 MemSizeB = 0;

    for (unsigned int i = 0; i < MapEntries; i++){
        EFI_MEMORY_DESCRIPTOR *desc = (EFI_MEMORY_DESCRIPTOR*)(Map + (i * DescSize));
        MemSizeB += desc->NumberOfPages * 4096;
    }

    Print(L"Size of memory: %dn", MemSizeB);

I hope that I will get help