How do you decide what numbers to use as the numerator and the denominator in each equivalent fraction to the given decimal?

For denominator the number of digits after the decimal are counted to find the multiple of 10s.

The numerator is the decimal number digits with the decimal removed.

Step-by-step explanation:

The given number of the decimal is used as the numerator and the denominator of the decimal always has to be 10 or a multiple of 10 depending on the position of the decimal point.

For example if we have a number 4.3

The numerator will be 43( the decimal is removed) and the denominator will be 10 because in the original decimal number 4.3 the decimal was before only 1 number that is 3.

Now take the example of 4.36

The numerator will be 436 ( the decimal is removed) and the denominator will be 100 ( 10 *10 = 100) because in the original decimal number 4.3 the decimal was before 2 number that is 3 and 6.

so the fraction will be 436/100

Now if we divide 436 by 100 we will get the same answer as the original number

100√436         4.36

        400

          360

          300

            600

          600

          xxx    

The same process is applied to bigger numbers such as 4.365 and so on.

If we have a number 43.6 the numerator will be 436 ( the decimal is removed) and the denominator will be 10 because in the original decimal number 43.6 the decimal was before 1 number that is 6.

so the fraction will be 436/10

If we have a number 436.5  the numerator will be 4365 ( the decimal is removed) and the denominator will be 10 because in the original decimal number 436.5 the decimal was before 1 number that is 5.

so the fraction will be 4365/10

For denominator the number of digits after the decimal are counted to find the multiple of 10s.

The numerator is the decimal number digits with the decimal removed.

the answer to your question is b.