[egin{array}{l}
ceiling(frac{x}{y}) = floor(frac{{x + (y - 1)}}{y})\
floor(frac{x}{y}) = ceiling(frac{{x - (y - 1)}}{y})
end{array}]
[egin{array}{l}
ceiling(frac{x}{y}) = floor(frac{{x + (y - 1)}}{y})\
floor(frac{x}{y}) = ceiling(frac{{x - (y - 1)}}{y})
end{array}]