TenMarks teaches you how you can multiply fractions.
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Learn about Multiplication of Fractions Let’s learn about multiplication of fractions with other fractions. Two examples, the first one is -3/5×1/4. So, if we’re multiplying one fraction with another fraction, it’s pretty simple. You take the numerator of the first fraction, multiply that with the numerator of the second fraction and you do the same to the denominator. Let’s try it here. The numerator of the first one is -3 multiplied by the numerator of the second one is 1. Denominators are 5×4 which gives us -3×1 is -3. Denominator is 5×4 is 20, relatively easy to do. Let’s try the second one which gives us 5/12×-12/5. So again, I’ve got two different fractions. So, we take the numerator of the first one which is five multiplied by the numerator of the second one, so it’s -12. And now here, I’ve got 12×5. Since both of these have 5 and 12 in there, we could technically write this differently. We could multiply 5 with -12 and then divide by 5 which is the greatest common factor between the numerator and the denominator times 12÷5. So, 5÷5 would be 1. So, the top would be -12. The bottom would be 12, 12/12 is 1. So, the final answer would be -1. Quickly recapping what we’ve learned. If we’re multiplying a fraction with another, we multiply the numerators and the denominators together. Here, it’s -3/20. Similarly, if I’m multiplying a different type of fraction, numerator becomes 5×-12, denominator becomes 12×5. Since we have five both on the numerator and the denominator, we could remove it by dividing both the numerator and the denominator by five because it’s their greatest common factor anyway right between this two. They’re the same numbers and we’re left with -12/12 or -1. We could have also not done that and just played the multiplication which would have given us 5×-12 is -60, 5×12 is 60, 60/60 is -1 anyway. So, we would have arrived at the same answer. I was just showing you two different ways of getting them.
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