Saturday, February 15, 2014

Fractions and Conversion of Units

Dear all,

As promised, here is a list of some conversion of units which is an alarming problem when I was marking through your work this week. Some of you have forgotten about the conversion of units and this is important.

1kg = 1000g

1m = 100cm
1km = 1000m

1h = 60 min
1 min = 60 sec

Area of square -> side x side 
All sides of a square are similar.
Perimeter of a square -> 4 x one side

1 litre = 1000ml

Area of rectangle -> length x breadth
Perimeter of rectangle -> length + length + breadth + breadth

Recap on Fractions:

  • We did addition and subtraction of mixed numbers
  • When we add two mixed numbers, we first look at the denominators. If they are the same, we can proceed to add the fractions up. If they are not the same, we have to convert the denominators into a common same number first.
  • in 1 whole 1/3 + 2 wholes 1/3, we add the wholes up first and then the fractions to get 3 wholes 2/3
  • in 2 wholes 1/6 + 1 whole 1/3, we need to change the denominators into a same number first before addition takes place. 1 whole 1/3 = 1 whole 2/6. 
  • So, 2 wholes 1/6 + 1 whole 2/6 = 3 wholes 3/6 (This can be simplified into 3 wholes 1/2)

  • For subtraction of mixed numbers, if the numerator of the first number is bigger than the second number, then subtraction of mixed numbers becomes much easier.
  • E,g 5/6 - 1/3 = 5/6 - 2/6 (Change 1/3 = 2/6)
  • You will get an answer of 3/6
  • However, if the numerator of the first fraction is smaller than the second fraction, then we have to change both mixed numbers into improper fractions.
  • E.g 1 whole 1/6 - 2/3 = 1 whole 1/6 - 4/6 (2/3 = 4/6)
  • 1 whole 1/6 = 6/6 + 1/6 = 7/6
  • So, we take 7/6 - 4/6 = 3/6 (final answer)
Homework:
  • Revision Practice Paper 2 (By Monday)
  • Corrections for PTS Worksheet 1 and 2 if you have not passed up
  • Fractions (1) for those who have not passed up
Sincerely,
Mr Nelson Ong

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