The denominator of a fraction cannot be 0, because the denominator is equivalent to a divisor. Otherwise, the equation cannot be established, and the molecule can be equal to 0, because the molecule is equivalent to the dividend. It is equivalent to dividing 0 by any number. No matter what the denominator is, the answer is 0.

The horizontal line in the middle of the score is called fractional line, the number above the fractional line is called numerator, and the number below the fractional line is called denominator. Read it as a score.

The basic property of fraction: When numerator and denominator are multiplied or divided by the same number (except 0), the value of fraction will not change. Therefore, each score has an infinite number of equal parts. Using this property, we can be on and off.

There are three types of scores: true scores, false scores and scored scores.