What is 21/11 + 3/7?
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Here's how to add
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Step 1Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator. Now you multiply 21 by 7, and get 147, then we multiply 11 by 7 and get 77. Do the same for the second term. We multiply 3 by 11, and get 33, then multiply 11 by 7 and get 77. The problem now has new fractions to add:
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Step 2Since our denominators match, we can add the numerators. 147 + 33 = 180 This yields the answer
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Step 3The last step is to reduce the fraction if we can. To find out, we try dividing it by 2... Nope! So now we try the next greatest prime number, 3... Nope! So now we try the next greatest prime number, 5... Nope! So now we try the next greatest prime number, 7... Nope! So now we try the next greatest prime number, 11... Nope! So now we try the next greatest prime number, 13... Nope! So now we try the next greatest prime number, 17... Nope! So now we try the next greatest prime number, 19... Nope! So now we try the next greatest prime number, 23... Nope! So now we try the next greatest prime number, 29... Nope! So now we try the next greatest prime number, 31... Nope! So now we try the next greatest prime number, 37... Nope! So now we try the next greatest prime number, 41... Nope! So now we try the next greatest prime number, 43... Nope! So now we try the next greatest prime number, 47... Nope! So now we try the next greatest prime number, 53... Nope! So now we try the next greatest prime number, 59... Nope! So now we try the next greatest prime number, 61... Nope! So now we try the next greatest prime number, 67... Nope! So now we try the next greatest prime number, 71... Nope! So now we try the next greatest prime number, 73... Nope! So now we try the next greatest prime number, 79... No good. 79 is larger than 77. So we're done reducing. There you have it! Here's the final answer to 21/11 + 3/7
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