Unit 2 Summary

Pre-Algebra · Axiom Academy

SUMMARY Unit 2: Fractions, Decimals, and Percents A quick review of the three ways to write one value — and how to move freely between them. A fraction, a decimal, and a percent can be three names for the same value — , 0.75 , and are one number. To add or subtract fractions you need a common denominator ; to multiply you go straight across; to divide you flip and multiply . Divide to turn a fraction into a decimal, multiply a decimal by 100 to get a percent, and write a percent over 100 to get a fraction. Pick whichever form is easiest for the job — fractions for exact parts, decimals for arithmetic, percents for comparing and for money. Core Concept Fractions Are Numbers A fraction names part of a whole and also a division. The bottom number (denominator) says how many equal pieces the whole is cut into; the top (numerator) says how many you take. Every fraction sits at one exact spot on the number line. Equivalent fractions: multiply or divide top and bottom by the same number — . Watch out for: a bigger bottom number means smaller pieces, not a bigger value. Core Concept Operations with Fractions Add and subtract only after the denominators match. Multiplying and dividing are quicker — no common denominator needed. Divide: keep, flip, multiply — . Mixed numbers: rewrite as improper fractions first, then convert back. Decimals extend place value past the ones: tenths, hundredths, thousandths. They are just fractions whose denominators are 10 , 100 , 1000 , and so on.

This is the written version of the interactive lesson above. See the full Pre-Algebra course.