ACT Math · Lesson 6

Part I Review

A mixed review of Number and Quantity: complex numbers, exponents and radicals, vectors, and matrices, with no chapter labels.

Part I Review: Number and Quantity

This set mixes all three Part I chapters together with no chapter labels. Recognizing which skill a question needs is part of the difficulty here, not a given. Twenty questions test recognition across the full Number and Quantity Part. No calculator is required, though Desmos or a handheld may still help on a few.

Match the question to the tool

  • Rational or irrational? Simplify the number first. A square root of a perfect square, a terminating decimal, and a fraction of integers are all rational.
  • Powers of ii: divide the exponent by 44 and use the remainder; i2=−1i^2 = -1 whenever it appears in a product.
  • Complex division: multiply the top and bottom by the conjugate of the denominator.
  • Exponents: add exponents to multiply, subtract to divide, multiply for a power of a power; a rational exponent mn\frac{m}{n} means the nnth root raised to the mm power.
  • Radicals: pull out the largest perfect square, combine only like radicals, rationalize denominators, and check every radical-equation answer in the original equation.
  • Vectors: add components, then apply x2+y2\sqrt{x^2 + y^2} last.
  • Matrices: determinant is ad−bcad - bc; sums and scalar multiples are entry by entry; products use rows times columns and need matching inner dimensions.

Work each question, then check the one error that is easiest to make for that skill: a dropped negative sign, an extraneous root, or a subtraction done as an addition.

Practice set

Exam mode

Exam mode runs on the clock of the real section and holds the explanations until you submit. You then see your score and an explanation for each question.

  • The exam covers 20 questions.
  • A single timer of 23 min runs for the whole set.

Study mode

Study mode lets you answer each question at your own pace and shows the explanation as soon as you check your answer.

  • The 20 questions appear in a new order each session.
  • The explanation opens when you check each answer.