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(1) 2,8,25,50,75,100 Magic number is 431
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$$\left[\frac{75 + 25}{50}+2 \right]*\left[100+8 \right]\Rightarrow$$ For this one, 431/108 is 3.99 but can it be rounded to 4?
$$\left[\frac{100+8}{\frac{75}{2}-25}\right]*50\rightarrow$$ For this one, rats...result is 8.64 after dividing the first part; too bad it can't be 8.62! Does it have to be the exact number or can it be rounded to 8.6...if so, then 431.5!