Math with strings

Variables:

$var1='1'; $var2='2';

Example1:

$var1+1 prints out 2

Example2:

$var1+'1' prints out 2

Example3:

$var1+$var2 prints out 3

Example4:

$var1+(int)$var2 prints out 3

Example5:

$var1+'2 sheeps' prints out 3