Overview of IEEE 754 1985 Standard Binary Floating Point Arithmetic
 
---From: High Performance Computing, by Dowd and Severance

 
IEEE 754 FORTRAN C Bits Exponent Mantissa
Single REAL*4 float 32 8 23
Double REAL*8 double 64 11 52
Double Extended REAL*10 long double >=80 >=15 >=64

 
 
IEEE 754 Min number Max number Base 10 accuracy
Single 1.2 E -38 3.4 E +38 6-9 digits
Double 2.2 E -308 1.8 E +308 15-17 digits
Double 
Extended
3.4 E -4932 1.2 E 4932 18-21 digits

Single Precision:

seeeeeeeemmmmmmmmmmmmmmmmmmmmmmm

Double Precision:

seeeeeeeeeeemmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm