0 for example because 1 5 is rounded to 2 and 2 5 is rounded to 2 thus added result of 2 2 becomes 4 also 3 5 is rounded to 4 and 4 5 is rounded to 4 thus added result of 4 and 4 becomes 0 fig4 shows this state in fig4 open circles represent that values on the open circles are not taken solid circles in fig4 represent that values on the solid circles are taken therefore when the input signal ranges from 0 5 to 0 5 there is no output signal when the input signal is larger than 0 5 but less than 1 5 the output signal is 1 when the input signal ranges from 1 5 to 2 5 the output signal is 2 according to the negative round similarly when the input signal is smaller than 0 5 but larger than 1 5 the output signal is 1 when the input signal ranges from 1 5 to 2 5 the output signal is 2 having examined a point in which rounded off number is 0 5 by rounding a numeral is rounded such that the rounded numbers becomes even numbers such as when 0 5 becomes 0 1 5 becomes 2 0 5 becomes 0 and 1 5 becomes 2 the three rounding.