Decimals, Fractions, and Percents Mastery

1. Concepts

• Decimal Place Value and Rounding:
  Each digit in a decimal has a place value (tenths, hundredths, thousandths, etc.). Rounding means finding the nearest value based on a given place value.
• Changing Fractions to Decimals:
  Divide the numerator by the denominator. Example: 3/4 = 0.75.
• Changing Decimals to Fractions:
  Write the decimal over its place value and simplify. Example: 0.6 = 6/10 = 3/5.
• Comparing and Ordering Decimals:
  Align decimals by the decimal point and compare digits from left to right.
• Adding & Subtracting Decimals:
  Line up decimal points and add or subtract as with whole numbers.
• Adding & Subtracting Money:
  Treat money values as decimals. Always line up decimal points.
• Estimating Decimal Sums & Differences:
  Round numbers to estimate before adding or subtracting.
• Multiplying Decimals & Money:
  Ignore decimals, multiply, then count total decimal places in factors for the answer.
• Estimating Decimal Products:
  Round factors before multiplying for a quick estimate.
• Dividing Decimals:
  • By Whole Numbers: Divide as usual.
  • By Decimals: Move decimal points to make the divisor a whole number, then divide.
• Estimating Decimal Quotients:
  Round numbers so the division is easier to estimate.
• Understanding Percent:
  Percent means "per hundred." 45% = 45 out of 100 = 0.45.
• Percents & Fractions/Decimals:
  To change a percent to a fraction, write over 100 then simplify. To a decimal, divide by 100.
• Multiplying Percents and Fractions:
  Change percent to a fraction or decimal, then multiply as usual.