It always is correct WITH THIS SET OF DATA. Try adding a couple of zero(e)s at the end of each of the 3 numbers and watch "Msg 8115, Level 16, State 6, Line 12 - Arithmetic overflow error converting float to data type numeric." appear.
The FLOAT still works, and produces even stranger (but predictable) results of 1000164 and 1000192.
I prefer an overflow error instead of wrong data. You can specify a precision of 38 digits
Numeric data types that have fixed precision and scale.
decimal[ (p[ , s] )] and numeric[ (p[ , s] )]
Fixed precision and scale numbers. When maximum precision is used, valid values are from - 10^38 +1 through 10^38 - 1. The SQL-92 synonyms for decimal are dec and dec(p, s). numeric is functionally equivalent to decimal.
The maximum total number of decimal digits that can be stored, both to the left and to the right of the decimal point. The precision must be a value from 1 through the maximum precision of 38. The default precision is 18.
The maximum number of decimal digits that can be stored to the right of the decimal point. Scale must be a value from 0 through p. Scale can be specified only if precision is specified. The default scale is 0; therefore, 0 <= s <= p. Maximum storage sizes vary, based on the precision.