In the ABAP language, there are types that are predefined in every ABAP program. The table below shows the predefined ABAP types.
Type  Length  Standard length  Description 

b 
One byte 
One byte integer (internal) 

c 
1 to 65,535 characters 
One character 
Text field 
cursor 
As i 
As i 
Database cursor 
d 
Eight characters 
Date field (format YYYYMMDD) 

decfloat16 
Eight bytes 
Decimal floating point number with 16 decimal places 

decfloat34 
sixteen bytes 
Decimal floating point number with 34 decimal places 

f 
Eight bytes 
Binary floating point number with 16 decimal places 

i 
Four bytes 
Four byte integer 

n 
1 to 65,535 characters 
One character 
Numeric text 
p 
1 to 16 bytes 
Eight bytes 
Packed number (implementation depends on hardware platform) 
string 
Variable 
Text string 

s 
Two bytes 
Two byte integer (internal) 

t 
Six characters 
Time field (format HHMMSS) 

x 
1 to 65,535 bytes 
One byte 
Byte field 
xstring 
Variable 
Byte string 
The predefined ABAP types decfloat34 and decfloat16.
The information below describes the attributes of these data types.
The value range is 11E+370 to 1E398, 0, +1E398 to +1E+3701 for decfloat16 and 11E+6112 to 1E6176, 0, +1E6176 to 1E+61121 for decfloat34. The maximum precision is 16 decimal places or 34 decimal places, respectively.
Decimal floating point numbers with fractional portions or exponents cannot be declared directly in the program; instead, you have to use text literals whose content can be interpreted as a number. That is, a number in a mathematical, scientific, or commercial notation.
We recommend decimal floating point numbers if precision and a large range of values are of importance. They do not have the disadvantages of binary floating point numbers. These binary floating point numbers cannot represent each decimal number in their value range exactly. Decimal floating point numbers have a much larger value range and a higher level of precision than packed numbers. When you have to save space (main memory and database), use the decfloat16 type instead of decfloat34.
By using the EXACT addition of the COMPUTE statement, it is possible to force an exact calculation for decimal floating point numbers under certain circumstances. No rounding is permitted in exact calculations and it leads to an exception.
Internally, decimal floating point numbers are represented by a 16digit or 34 digit decimal mantissa and a decimal exponent. The exponent is between 383 and +384 or 6143 and + 6144, respectively.