A few problems involving evaluating by numerical substitution of expressions with variables are sprinkled in early on with little formal discussion. A formal section evaluating variable expressions occurs toward the end but is brief. Signed numbers are included by the end. The commutative, associative and distributive properties are not discussed, but problems applying them are present in examples and problem sets. The properties of equality are mentioned but not named as such.
Scientific notation is presented in two sections, one for large numbers and one for small.
The unit on multiplying numbers in scientific notation is a nice addition. This skill is often lacking in pre-algebra texts. Aside from scientific notation, negative exponents are not used, nor are generalized multiplication and division involving exponents with a common base. Powers and roots of variable expressions are not considered, but there are some interesting multistep simplifications with whole number powers. The level of difficulty is only average.