Vedic Mathematics (Maths) Addition and Subtraction of Fractions ADDITION AND SUBTRACTION OF FRACTIONS
The usual method using common denominators is cumbersome and difficult to learn. By contrast the Vedic method allows the answer to be written straight down.
We multiply crosswise and add to get the numerator of the answer and we multiply the denominators to get the denominator of the answer.
This looks like “horizontally and crosswise” rather than “vertically and crosswise” but fractions can also be written: 2/3 + 4/7, in which case we have:
in which we see “vertically and crosswise”.
Subtraction is similar, we cross-multiply and subtract:
When the denominators are not relatively prime we may divide out the common factor and cross-multiply with these reduced figures (see Williams & Gaskell 1997).