 For example, if one starts with a NaN and adds 1 five times in a row, each addition results in a NaN, but there is no need to check each calculation because one can just note that the final result is NaN.However, depending on the language and the function, NaNs can silently be removed from a chain of calculations where one calculation in the chain would give a constant result for all other floating-point values.For example, the calculation "x"0 may produce the result 1, even where "x" is NaN, so checking only the final result would obscure the fact that a calculation before the "x"0 resulted in a NaN.