Programming in Lua : 3.5

Part I. The Language Chapter 3. Expressions

3.5 - Precedence

Operator precedence in Lua follows the table below, from the higher to the lower priority:

             ^
             not  - (unary)
             *   /
             +   -
             ..
             <   >   <=  >=  ~=  ==
             and
             or

All binary operators are left associative, except for `^´ (exponentiation) and `..´ (concatenation), which are right associative. Therefore, the following expressions on the left are equivalent to those on the right:

    a+i < b/2+1          <-->       (a+i) < ((b/2)+1)
    5+x^2*8              <-->       5+((x^2)*8)
    a < y and y <= z     <-->       (a < y) and (y <= z)
    -x^2                 <-->       -(x^2)
    x^y^z                <-->       x^(y^z)

When in doubt, always use explicit parentheses. It is easier than looking up in the manual and probably you will have the same doubt when you read the code again.