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Chapter 7: Decimals
- 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
- 4 decimal places
- The number of digits after the decimal
point tell us the number of decimal
places in a decimal
- 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
- The number of decimal places in the
decimal gives the number of zeros in
the denominator of the fraction
- To convert from decimals to fractions:
- 7-03 Adding and
subtracting decimals
- 1. Line up the decimal points
- 2. Fill gaps with zeros
- 3. +/- as normal
- 3. +/- as normal
- 2. Fill gaps with zeros
- 1. Line up the decimal points
- 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
- 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
- Move the decimal point one place to the
left for each zero in the power of ten
- To multiply a decimal by a power of ten:
- 7-05 Multiplying decimals
by estimating
- Rounding the number to closest
- Multiply as usual
- Estimation done
- Can be use to check answer
- Can be use to check answer
- Estimation done
- Multiply as usual
- Rounding the number to closest
- 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
- 2. Insert decimal point so that the answer has the
same number of decimal places in the question
- 1. Ignore decimal point and multiply numbers
- 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
- 3. Add zeros to the end of the
decimal being divided, if needed
- 2. make the decimal point in the answer line
up with the decimal point in the question
- 1. rewrite question in short division form
- When dividing a decimal b a whole number:
- 7-08 Dividing decimals
- Apply knowledge of equivalent fractions
- 40/30 = 4/3 = 0.4/0.3 = 0.04/0.03
- 40/30 = 4/3 = 0.4/0.3 = 0.04/0.03
- Apply knowledge of equivalent fractions
- 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
- Have a definite number of decimal places
- RECURRING
- Are decimals whose digits repeat endlessly
- Are decimals whose digits repeat endlessly
- When fractions are converted to decimals, the
decimals can be TERMINATING and RECURRING
- 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
- To round a decimal 'cut it at the required decimal
place and look at the digit in the next place:
- 7-11 Decimal problems
- Read carefully
- Show working
- Word answer
- Read carefully
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