Default length for numerical variable？

shiyiming

data hua1;
input num @@;
cards;
123456789.123 12345678901.123 123456789012.123 123456789123456
;

Here, want to ask what the default length of variable num? I am confused why SAS tutorial says the default length of numerical variable is 8? Thanks a lot!

shiyiming

快去补计算机基础知识,先搞明白,八个BYTE与八个数位的区别.