THE multiplication of fractions can be, at first sight, something challenging, because it is a multiplication of numbers that are being divided, however your calculation is simple and very fast, contrary to what is imagined, since its resolution does not take into account the quotient of the fraction.
Read too: Fraction simplification: know how to do it
How do you do multiplication with fractions?
Fractions are part of the set of rational numbers. This set can be written as follows:
The set of rational numbers have very well defined operations, that is, when using two numbers from this set in any of the fundamental operations, including multiplication, the result will also be a rational number.
The multiplication of fractions is performed multiplying the numerator of the first fraction with the numerator of the second fraction and then multiplying the denominator of the first with the denominator of the second. The operation continues successively in cases where the multiplication involves more than two fractions.
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See the general form.
Be The, B, ç and d whole numbers with B ≠ 0 and d ≠ 0, so it is valid that:
→ Examples
Sign game in the multiplication of fractions
The numerator and denominator are whole numbers, therefore, fractions inherit some properties of this set, such as the sign game:
first number sign |
second number sign |
result sign |
+ |
+ |
+ |
+ |
- |
- |
- |
+ |
- |
- |
- |
+ |
Also know: Equivalent fraction: what is it?
Exercise solved
question 1 – It is known that the product between the ratios between x and 4, e, 5 and 2 is equal to 30. Determine the value of x.
Solution
We must carry out the multiplication between the reasons, therefore:
by Robson Luiz
Maths teacher
Would you like to reference this text in a school or academic work? Look:
LUIZ, Robson. "Multiplication of fractions"; Brazil School. Available in: https://brasilescola.uol.com.br/matematica/multiplicacao-com-fracao.htm. Accessed on June 27, 2021.
