What is 21/63 + 4/10?
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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 10, and get 210, then we multiply 63 by 10 and get 630. Do the same for the second term. We multiply 4 by 63, and get 252, then multiply 63 by 10 and get 630. The problem now has new fractions to add:
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Step 2Since our denominators match, we can add the numerators. 210 + 252 = 462 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... Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:
So far so good... let's try to divide by that number again. No good. So next you try the next prime number, which is 3... Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:
So far so good... let's try to divide by that number again. No good. So next you try the next prime number, which is 5... No good. So next you try the next prime number, which is 7... Are both the numerator and the denominator evenly divisible by 7? Yes! So we reduce it:
So far so good... let's try to divide by that number again. No good. So next you try the next prime number, which is 11... No good. So next you try the next prime number, which is 13... No good. 13 is larger than 11. So we're done reducing. And we're done! Here's the final answer to 21/63 + 4/10
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