How does one find the common denominator in a fraction.....?

Answer 1

To find the common denominator between fractions simply multiply the denominators and this is the common denominator.

However this number may be large so try and find a number that all denominators will divide into evenly.

Hope this helps.

Answer 2

The general way of finding the greatest common divisor (denominator) is this way:

If a and b are the two values, always let a <= b, if a > b, swap the values of the two variables.

Do the following while still no of the variables is 0:
1. calculate b (mod a), the rest after dividing b by a. Set b to this value. Or simply draw a from b until b is smaller than a.
2. Since a is now > b, swap the two values.

When that is finished a should be 0 and b should not be 0. b now contains the value of the greatest common denominator (of the two original values of a and b).

For example: Let's say we have the two values 39 and 102.

So a = 39 and b = 102.

Set b = 102 (mod 39) = 24
Swap a and b.
Now a = 24 and b = 39.

Set b = 39 (mod 24) = 15
Swap a and b.
Now a = 15 and b = 24

Set b = 24 (mod 15) = 9 and swap
Now a = 9 and b = 15

Then a will be = 6 and b = 9
Then a = 3 and b = 6
Finally a = 0 and b = 3. Since a = 0, break here.

So since b now is 3, the common denominator of 102 and 39 is 3.

This method also works for non-integers, for example rational number. However, it doesn't work if a/b is irrational.

Answer 3

To find common denominator in fraction problem multiply the denominators of each fraction. This will be the common denominator of each fraction that has both equal and unequal denomiators FOR EXAMPLE ; 1/2, 1/7,1/3 would be common denominator of 42 (2X7X 3=42)1/2=21/42, 1/7 =6/42 and 1/3=14/42.

Answer 4

In order to add a fraction, the pieces or slices must be the same size.

1/3 + 1/2 are not same size pieces, so you have to do the following:

split the 1/3 into 2 pieces and split the 1/2 into 3 pieces.

now, everything is in 1/6 pieces. they are all the same size, so...

you can compare them...

for your sake, draw two circles, one split into thirds (draw a capital Y inside the circle) and one split in half.

shade in the 1/3 piece. split the shaded and unshaded pieces in halves.

shade in the 1/2 on circle #2 and split the shaded and unshaded into three pieces.

do you see 6 pieces in each circle if you count all the pieces?

the sum is when you just add up the shaded pieces in both circles.

because technically, you cannot add 1/3 with 1/2 and call it two pieces out of 5. cause everyone would want to have the 1/2 piece over the 1/3 piece.

when you have bigger numbers like 3/15 + 2/18,

what you might want to do is simplify the fractions...

3/15 = 1/5
2/18 = 1/9

then the short cut in finding the least common denominator would be to multiply top and bottom of fraction by the opposite denominator.

1x9=9
----------
5x9=45

1x5=5
---------
9x5=45
----------------------------
9+5=14
----------
45,45=45

then this final answer will be simplified. you never add the bottom number of the fraction (denominator) because it is already the total number of pieces in one circle. the answer of the fraction is represented out of a whole, NOT out of two wholes.

if you don't simply the fractions before you divide them, you would have a bigger number to simplify at the end.

Answer 5

Common Factors First Method.

1. Factor each demonimator -- usually factor as a prime factorization.
2. List the common factors, the factors each fraction shares, writing that factor only once.
3. Add to the list the factors each fraction does not share, listing only once the ones they have in common with some of the other fractions.
4. The list of factors is the common denominator. Multiply the factors together if needed.

One Fraction At-A-Time Method.
1. Factor each demonimator -- usually factor as a prime factorization.
2. List each factor of the first fraction.
3. Add to the list the factors of the second fraction which have not already been listed.
4. Repeat step 3 for each fraction.
5. The list of factors is the common denominator. Multiply the factors together if needed

Answer 6

If you want a common denominator for the purpose of adding/subtracting two fractions, the simplest way is to use the product of the two denominators, unless a smaller number is obvious. Convert both fractions to the common denominator, do the sum, then reduce the result to lowest form.

Answer 7

u divide the numerator and denominater to the possible # by the same number

Answer 8

do LCM