pwd
mkdir 0224
cd 0224

perl -d -e 1		# debug one line at a time, q to quit debug mode

DB<1> print 1.25	# print a floating point 1.25
DB<2> print 255.000	# 255

math operator    + - * / %
1+1
10%2             #module

string operator  x .
x               #mean multiple
.               #mean append

this . is       #append is after this
a x 3           #aaa

0377            #oct 377 ie 255
0xff            #hex ff  ie 255
0b11111111      #binary ie 255