- Confusing the formula for C and A (C requires Diameter; whereas A needs the square of the radius) ;
- Mistook radius for diameter or vice versa;
- Using the wrong value of pi for the wrong accasion;
- Missing units in the final answer
- Using the wrong units for the answer (m, cm, m2, cm2):

- "m" instead of "cm" or vice versa

- Using square unit (cm2) in place of a length unit (cm) for perimeter or vice versa for area.

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Pg 29

Q(e) --> Missing out the 2 R

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Pg 30

Q3

1st problem

--> 56.55 ?? (actual: 56.54866776)

2nd problem

--> pi x 9 is "pi x R" ???!!! , But C = pi. D

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Pg 34 (problem with rounding off?)

Q3(b) 5538.96 ~ 5539.0 , Many with 5538.1 ???

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Pg 36