%d for decimal integers


puts '%d' % 10         # => '10': %d for decimal integers

1.	Display a Message
2.	Insert some output from a shell command
3.	Put two or more variables together with the + method:
4.	format a string with puts
5.	format based string interpolation
6.	Get the command line parameter
7.	Comparing Floating-Point Numbers
8.	Simple Arithmetic
9.	use parentheses
10.	Array on righthand side for multiple args
11.	hexadecimal integers
12.	uppercase hexadecimal integers
13.	octal integers string format
14.	full-length floating-point numbers
15.	force exponential notation
16.	exponential with uppercase E
17.	six significant digits
18.	Use %f or %e depending on magnitude
19.	Field width
20.	Float number Precision
21.	Field and precision combined
22.	Multiple arguments to be formatted

%d for decimal integers : puts « Language Basics « Ruby