# Common Core MATH 8 NS 2 Grade 8 The Number System Know That There Are Numbers That Are Not Rational And Approximate Them By Rational Numbers

**The Number System: Know That There Are Numbers That Are Not Rational, And Approximate Them By Rational Numbers.**

Use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram, and estimate the value of expressions (e.g., ?2). For example, by truncating the decimal expansion of ?2, show that ?2 is between 1 and 2, then between 1.4 and 1.5, and explain how to continue on to get better approximations.