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Add and Subtract Fractions

Fractions · Class VI

Slide two fractions a/b and c/d. See their sum and difference as decimals.

1
type a value
110
2
type a value
110
1
type a value
110
3
type a value
110
Live values
  • a/b0.5
  • c/d0.3333
  • Sum0.8333
  • Difference0.1667
Live readout
a/b0.5
c/d0.3333
Sum0.8333
Difference0.1667
Numerator a1
Denominator b2
Numerator c1
Denominator d3

Formulas in this lab

  • a/b
    ab\dfrac{a}{b}
  • c/d
    cd\dfrac{c}{d}
  • Sum
    ad+bcbd\dfrac{ad + bc}{bd}
  • Difference
    ad−bcbd\dfrac{ad - bc}{bd}
Tip: Common denominator b times d makes the addition straightforward.

Frequently asked questions

▶How do I add two fractions with different denominators?

Find a common denominator and then add the numerators. So 1/2 + 1/3 becomes 3/6 + 2/6 = 5/6. The lab shows the result as a decimal, so 1/2 + 1/3 displays as about 0.833.

▶How do I use the add and subtract fractions lab?

Set the numerators a, c and denominators b, d. The lab displays a/b + c/d and a/b - c/d as decimals so you can match them with the textbook fraction answer. Try 3/4 and 1/2 to see 1.25 and 0.25.

▶Where do fraction sums appear in daily life?

Pizza slices and roti pieces are a classic example. If you eat 3/8 of a roti and your sibling eats 1/4, together you ate 3/8 + 2/8 = 5/8, leaving 3/8. The lab gives the decimal value 0.625 to confirm.

▶Fraction addition vs decimal addition: which is easier?

Fractions stay exact: 1/3 + 1/3 = 2/3 with no rounding. Decimals can lose accuracy because 1/3 becomes 0.333... For school work, fractions are safer; for shop bills, decimals are faster. The lab shows both so you can compare.