Explanation
The data type of gv_result in the assignment data (gv_result) = 1/8 will be TYPE DECFLOAT 16. This is because the assignment operator (=) in ABAP performs an implicit type conversion from the source type to the target type, according to the following rules12:
If the target type is specified explicitly, the source value is converted to the target type.
If the target type is not specified explicitly, the source type is used as the target type, unless the source type is a literal or an expression, in which case the target type is determined by the following priority order: DECFLOAT34, DECFLOAT16, P, F, I, C, N, X, STRING, XSTRING.
In this case, the target type is not specified explicitly, and the source type is an expression (1/8). Therefore, the target type is determined by the priority order, and the first matching type is DECFLOAT16, which is a decimal floating point type with 16 digits of precision12.
References: 1: ABAP Assignment Rules - ABAP Keyword Documentation - SAP Online Help 2: ABAP Data Types - ABAP Keyword Documentation - SAP Online Help