Understanding Decimals

Pre-Algebra · Axiom Academy

A decimal is just a fraction in disguise — the digits to the right of the point ARE tenths, hundredths, and thousandths. Decimals are another way to write fractions — especially fractions with denominators of 10, 100, 1000, and so on. The decimal point separates the whole-number part from the fractional part, and each place to the right stands for a power of 10 in the denominator. Each place to the right of the point is a power of ten below When we cut a whole into 10 equal parts , each part is one tenth — written as the fraction or the decimal 0.1 . The first digit after the point is the tenths place, so 0.3 means 3 tenths . Cut the whole into 100 equal parts and each part is one hundredth. A grid shows hundredths perfectly: every little square is . The second digit after the point is the hundredths place, so 0.25 means 25 hundredths . Because 0.25 has two decimal places, we read it as "twenty-five hundredths." (Saying "two tenths and five hundredths" is also correct — it's just the long way.) 4. Equivalent Fractions and Decimals A decimal fraction often simplifies to one with a smaller denominator. Watch the 25 shaded squares of regroup into a single quarter of the whole — that's how . The same trick works for any decimal fraction. Here are four common ones, each in lowest terms: 5. Reading and Writing Decimals Reading a decimal out loud is really just naming the place value of its last digit . That place also tells you the denominator when you convert to a fraction.

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