Chapter 7: Decimals

Chapter 7: Decimals

1. 7-01 Ordering Decimals

   • The number of digits after the decimal point tell us the number of decimal places in a decimal
   • 3.6567
     • 4 decimal places

2. 7-02 Decimals and fractions

   • To convert from decimals to fractions:
     • The number of decimal places in the decimal gives the number of zeros in the denominator of the fraction

3. 7-03 Adding and subtracting decimals

   • 1. Line up the decimal points
     • 2. Fill gaps with zeros
       • 3. +/- as normal

4. 7- 04 Multiplying and dividing decimals by powers

   • To multiply a decimal by a power of ten:
     • Move the decimal point one place to the right for each zero in the power of ten
   • To divide a decimal by a power of ten:
     • Move the decimal point one place to the left for each zero in the power of ten

5. 7-05 Multiplying decimals by estimating

   • Rounding the number to closest
     • Multiply as usual
       • Estimation done
         • Can be use to check answer

6. 7-06 Multiplying decimals

   • 1. Ignore decimal point and multiply numbers
     • 2. Insert decimal point so that the answer has the same number of decimal places in the question

7. 7-07 Dividing decimals by whole numbers

   • When dividing a decimal b a whole number:
     • 1. rewrite question in short division form
       • 2. make the decimal point in the answer line up with the decimal point in the question
         • 3. Add zeros to the end of the decimal being divided, if needed

8. 7-08 Dividing decimals

   • Apply knowledge of equivalent fractions
     • 40/30 = 4/3 = 0.4/0.3 = 0.04/0.03

9. 7-09 Terminating and recurring decimals

   • When fractions are converted to decimals, the decimals can be TERMINATING and RECURRING
   • TERMINATING
     • Have a definite number of decimal places
   • RECURRING
     • Are decimals whose digits repeat endlessly

10. 7-10 Rounding decimals

    • To round a decimal 'cut it at the required decimal place and look at the digit in the next place:
    • If the digit is less than 5 round down
    • If the digit is 5 or more round up

11. 7-11 Decimal problems

    • Read carefully
    • Show working
    • Word answer

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