When doing rounding, please take note of the following:
A A = price without GST
B B = GST
C C = price with GST
Formula
A A + B = C
Method 1:
- A =
- round (
- C * 100 / 106)
- B = C -
- A
Method 2:
- B =
- round (
- C * 6/106)
- A = C -
- B
Method 1 will give you more accurate figure. Method 2 will give you bigger rounding error. I know the difference is subtle, but rounding a number gives you higher precision when the number of significant figures are bigger. (Maths and physics in O level / SPM).
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