Common Core · Grade 8
8.NS.A.2
Grade 8 — Use rational approximations of irrational numbers to compare them and locate them approximately on a number line.
Grade 8 — Use rational approximations of irrational numbers to compare them, locate them on a number line and estimate expressions.
The 2 skills that cover it
- Square & Cube RootsUndo a square or a cube: find the root of a perfect square or cube, solve x^2 = p and x^3 = p, and estimate the roots that are not whole numbers.Read the lesson →
- Rational & Irrational NumbersSort the real numbers: every fraction is a decimal that stops or repeats, every other decimal is irrational, and both kinds have a place on the number line.Read the lesson →
What a student should be able to do
- Evaluate square roots of perfect squares and cube roots of perfect cubes.
- Solve equations of the form x2 = p and x3 = p, remembering both square roots.
- Estimate a non-perfect square root between two whole numbers and to one decimal place.
- Use roots to find the side of a square or the edge of a cube from its area or volume.
- Decide whether a number is rational or irrational and explain why.
- Convert a fraction to a terminating or repeating decimal, and a repeating decimal back to a fraction.
- Approximate an irrational number such as sqrt(10) or pi and place it between two rationals.
- Order a mixed set of fractions, decimals, roots and pi from least to greatest.