Tham KY's answer to riz's Primary 6 Maths Data Analysis Singapore question.
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not a standard way to present the workings, more on analytical skills... wish you understand the steps... pls verify...
Date Posted:
4 years ago
Another way to think of it is this.
1, 2 and 9 are three factors of the six available factors for the number to be found.
Observe that 1 itself and 2 itself are in their simplest forms, while 9 can be rewritten as 3 x 3.
There must be an existing factor 3 as well. Let’s add this to the list...
1, 2, 3, 9
There are two more factors. If you realise that 2 and 3 are factors which are unrelated, we can multiply them together to form another factor 6. Let’s add this to the list...
1, 2, 3, 6, 9
Similarly, 2 and 9 are unrelated factors (because nothing is common in 2 and 9 other than 1), so we multiply this together to form the final factor 18. Your final list is...
1, 2, 3, 6, 9, 18
Check that 1 x 18 = 2 x 9 = 3 x 6 = 18, so these make up the six factors of your number which must be 18.
The larger number is 5 times of this, or 90.
1, 2 and 9 are three factors of the six available factors for the number to be found.
Observe that 1 itself and 2 itself are in their simplest forms, while 9 can be rewritten as 3 x 3.
There must be an existing factor 3 as well. Let’s add this to the list...
1, 2, 3, 9
There are two more factors. If you realise that 2 and 3 are factors which are unrelated, we can multiply them together to form another factor 6. Let’s add this to the list...
1, 2, 3, 6, 9
Similarly, 2 and 9 are unrelated factors (because nothing is common in 2 and 9 other than 1), so we multiply this together to form the final factor 18. Your final list is...
1, 2, 3, 6, 9, 18
Check that 1 x 18 = 2 x 9 = 3 x 6 = 18, so these make up the six factors of your number which must be 18.
The larger number is 5 times of this, or 90.
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