Converting fractions into decimals is the result of calculating fractions. The topic in the picture is typical, the denominator is 1 followed by several zeros, and this score is easy to calculate. 10 1 That is to divide 1 by 10, which is 0. 1, and so on. You can use a rigid method to calculate the zero after 1, and then move the decimal point of the molecule from right to left by several digits, and then point the decimal point.

Let's put it this way, 3/ 10, and the molecule is 3. In fact, it is 3.0 written in decimal point, and the denominator is 10, which is 1 zero to the right, so the decimal point of the molecule is moved to the left by 1 bit, which is 0.3 expressed in decimal point;

9 1 100, the numerator is 91,namely 9 1.0, and the denominator is100. The denominator has two zeros after 1 Using the method mentioned above, the molecule has two digits from right to left, which is 0.9 1.

3/ 10+5/ 10=0.3+0.5=0.8

9 1/ 100-75/ 100=0.9 1-0.75=0. 16

42/ 1000+ 15/ 100=0.042+0. 15=0. 192

6/ 10-38/ 100=0.6-0.38=0.22

Extended data:

Fractions and decimals can be divided into three situations:

1. Fractions are converted to finite decimals. The necessary and sufficient condition for the simplest fractional reduction to a finite decimal is that the prime factors of the denominator are only 2 and 5.

2. Fractions are converted into pure circular decimals. The necessary and sufficient condition for the simplest fraction to be converted into a pure cyclic decimal is that there are no 2 and 5 in the prime factor of the denominator, and the number of digits in the cyclic segment is equal to the number of 9 in the minimum number of 99…9 that can be divisible by the denominator of the simplest fraction.

3. Divide the score into mixed cycle decimals. A necessary and sufficient condition for simplest fraction to be converted into a mixed cyclic decimal is that the denominator contains both prime factors 2 or 5 and prime factors other than prime factors 2 and 5.

In the converted mixed cyclic decimal, the number of acyclic digits is equal to the greater of the exponent of factor 2 or factor 5 in the denominator; The number of digits in the loop segment is equal to 9 in the form of 99…9, which can be divisible by factors different from 2 and 5 in the denominator.

The method of converting fractions into decimals according to the relationship between fractions and decimals. For example, when converting to decimals, we can know that the rewritten decimals are two digits according to "two digits after the decimal point represent a few percent", so =0.37.

When a fraction is rewritten as a decimal, there are not enough digits in the decimal part, so zero should be added. For example, it should be 0. 007 if converted to decimal.

References:

Baidu Encyclopedia-Fractional Decimal