>>>You could convert to currency as the number of digits for the integer part of currency is 14.9649
>>>

>>>?log10($922337203685477)
>>>

>>>
>>>But that is also taking 8 bytes - as the DateTime field
>>
>>Currency is a double integer and datetime is two integers.
>
>
>Actually, I believe a DateTime is a double, where the seconds are stored in the fractional part

Believing is a personal matter, I wouldn't get into that. But I wrote code to rebuild crashed tables, back in the dark ages when tables used to crash, so I had to know the structure of each data type. It's two integers, believing is not required.