Here’s the way to do it: Cross-multiply the two fractions and add the results together to get the numerator of the answer. Suppose you want to add the fractions 1/3 and 2/5. To get the numerator of the answer, cross-multiply. In other words, multiply the numerator of each fraction by the denominator of the other: 1*5 = 5 2*3 = 6 Add the results to get the numerator of the answer: 5 + 6 = 11 Multiply the two denominators together to get the denominator of the answer. To get the denominator, just multiply the denominators of the two fractions: 3*5 = 15 The denominator of the answer is 15. Write your answer as a fraction. Because the numerator and the denominator are both even numbers, you know that the fraction can be reduced. So try dividing both numbers by 2: This fraction can’t be reduced further, so 37/40 is the final answer. In some cases, you may have to add more than one fraction. The method is similar, with one small tweak.
Add fractions with the quick trick methodYou can’t always use this method, but you can use it when one denominator is a multiple of the other. Look at the following problem:First, solve it the easy way: Those are some big numbers, and you’re still not done because the numerator is larger than the denominator. The answer is an improper fraction. Worse yet, the numerator and denominator are both even numbers, so the answer still needs to be reduced. With certain fraction addition problems, there is a smarter way to work. The trick is to turn a problem with different denominators into a much easier problem with the same denominator. Before you add two fractions with different denominators, check the denominators to see whether one is a multiple of the other. If it is, you can use the quick trick:
Add fractions the traditional wayUse the traditional way only when you can’t use either of the other methods (or when you know the least common multiple [LCM] just by looking at the denominators).Here’s the traditional way to add fractions with two different denominators:
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How do you add fractions with unlike denominators step by step?To add fractions with unlike denominators, you should:. Find the common denominator.. Rewrite each fraction using the common denominator.. Add the numerators.. Carry across the common denominator.. If possible, reduce the final fraction.. What is the easiest way to add fractions with unlike denominators?You simply use the product of the two denominators as a common denominator. Then, in order to bring both fractions on that common denominator you only need to multiply the numerator of each by the denominator of the other. Easy!
How do you teach students to add fractions?All you need to do is follow three simple steps: Step 1: Find a common denominator. Step 2: Add the numerators (and keep the denominator) Step 3: Simplify the fraction.
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