How many significant numbers should there be in the answers to the multiplications?

a) [[$ \text{5.26} \cdot \text{5.056} \cdot \text{0.0068} $]]


b) [[$ \text{2.01263} \cdot \text{1.02} $]]


c) [[$ \text{0.06} \cdot \text{7.014} \cdot \text{0,00581} $]]