Math - Chapter 4 - Decimals
Comparing Fractions and Decimals
1. Change fraction to decimal. 2. Line-up to compare which is larger.
Decimals
1. Decimals have three parts. A. Whole number B. Decimal point C. Decimal part 3.852
Order of Operations Please Excuse my dear Aunt Sally.
1. Grouping Symbols 2. Exponents 3. Multiply and Divide (Left to Right) 4. Add and Subtract (Left to Right)
Changing Fractions to decimals
1. If it will continue repeating forever, we put a bar over the number the first time it occurs after the decimal point. 2. If you have mixed number, it is only necessary to divide the fraction part of each will be the same.
Comparing decimals
1. Line up decimals according to place value (decimal above decimal). 2. Compare digits in same place value (left to right). 3. When 2 digits are not equal: number with larger digit is larger decimal. 13.208 < 13.28 .12 > .086
Adding Decimals
1. Line up numbers so decimal points line up vertically. 2. Add digits from Right to Left -- Carry is more than 9. 3. Put decimal in answer so it is line up vertically with other decimals.
Subtracting Decimals
1. Line up numbers so decimal points line up vertically. 2. Subtract digits from Right to Left --- borrow if necessary. 3. Put decimal in answer so it is line up vertically with other decimals.
Rounding Decimals
1. Locate digit in rounding location. 2. Check digit to its right. 3. If it is 5(+), and add one to rounding location (round up). 4. If it is 4 (-), keep rounding location the same (round down). 5. Drop all digits to right of rounding location is in the decimal part of the number (else fill in with zeros to decimal).
Dividing by a decimal
1. Move the decimal in move to Right until divisor is a whole number. 2. Move the decimal point in the dividend to the right the same number of places. 3. Place the decimal point in the divided. 4. Divide.
Multiply decimals
1. Multiply as though they are whole numbers. 2. Put decimal in answer: number decimal places (product) = sum of places in factors ( count from the right).
Dollar to Cents
1. Multiply same multiplying by 100. 2. Move decimal two places to Right. 3. Change dollar sign to cents sign.
Write Word Name as Decimals
1. Number before "and" is the whole number. 2. "And" = decimal point. 3. Number after "and" is the decimal point. Two and thirty-eight thousands. 2.038 Three hundred and ninety-six hundredths. 300.96
Dividing decimal by whole number
1. Place decimal point in quotient directly above the decimal in the divided. 2. Divide as with whole numbers. 3. If necessary add zeros.
Multiply by power of 10
1. Product will be larger because number > 1. 2. Move decimal to the Right same number of zeros in power of 10.
Decimals and Fractions
1. Put number in decimal part over place value of last digit. 2. Simplify 0.51 = 51/100 0.12 = 12/100
Estimating with decimals
1. Round up or down first. 2. Do Math process. 3. Difference means to subtract. 4. Sum means to Add. 5. Product means to Mulitiply. 6. Quotient means to divide.
Cents to Dollar
1. Same as multiplying by (.01) 2. Move decimal two places to the left. 3. Change cent sign to Dollar sign.
Multiply by .1, .01, 001
1. The product will be smaller because multiply by number 1. 2. Move decimal to Left same number places in .1, .01, 001.
Writing Decimals in Words
1. Write whole numbers part in words 2. Write "and" for the decimal point. 3. Write decimal part in words followed by place value of the last digits. 8.7 Eight and seven tenths. 97.28 Ninety-seven and twenty-eight hundredth.
Place Value in Decimals
Millions Hundred-thousands Ten-thousands Thousands Hundreds Tens Ones . Decimal Tenths Hundredths Thousandths Ten-thousandths Hundred-thousandths Millionths
Billion
Nine zeros
Special Fractions to Decimals
Put last digit of numerator in place value of denominator. 12/100 = 0.12 173/10 = 17.3
Rounding to cents
Rounding to cents - round to hundreds place value location.
Rounding to dollars
Rounding to dollars - round to ones place value location.
Millions
Six zeros
Trillion
Twelve zeros
