Unfortunately, there is no "easy" way to add and subtract fractions, really-you always have to find a common denominator. If you can't be bothered finding one right away, it may at least be a bit easier to save this step for the end.
For example, instead of finding a common denominator before adding 4 / 13 and 22 / 42, start by simply multiplying the fractions by 42 / 42 and 13 / 13, respectively. This gives us 168/546 + 286/546 = 454/546. You can see that these are divisible by 2, so we have 227 / 273.
(Note that this is a somewhat situational example, in that the fraction cannot be reduced from 546 if some numbers are added, e.g. 546 is not divisible by 5, so 5/546 could be a final answer.)
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no, to add and subtract like and unlike fractions the denominator has to be the same,
The fastest and surest way to do that is to have a calculator that has a fraction button. (a b/c)
What do you get when you add 1/2 and 1/4 ? You can't even do that simple addition without first changing both fractions to something common, even if you do it in your head and do it so fast that you don't realize you're doing it. The only answer to the question is simply: There's no way to add or subtract fractions if they don't have the same denominator, and if you do, then you get the wrong answer.
Finding a common denominator makes it possible to add two fractions because it allows us to write each fraction as a multiple of a common (usually smaller) fraction. Subtracting fractions works the same way; find a common denominator so that the fractions involved are in the same terms.
just change the fration with the smallest denominator and add or subtract the way you always do.