# Subtract fractions: 15/16 - 1/8 = ? Subtraction of ordinary (simple, common) fractions, result explained

## The latest subtracted fractions

 15/16 - 1/8 = ? Feb 22 10:25 UTC (GMT) 17/36 - 3/16 = ? Feb 22 10:24 UTC (GMT) 4/15 - 1/6 = ? Feb 22 10:24 UTC (GMT) 13/3 - 7/158 + 45/17 = ? Feb 22 10:24 UTC (GMT) 12/20 - 1/5 = ? Feb 22 10:24 UTC (GMT) 12/20 - 1/5 = ? Feb 22 10:24 UTC (GMT) 11/15 + 10/10 = ? Feb 22 10:23 UTC (GMT) 55/25 + 8 = ? Feb 22 10:23 UTC (GMT) 19/15 - 1/2 = ? Feb 22 10:23 UTC (GMT) 53/294,233 - 34/63 = ? Feb 22 10:23 UTC (GMT) 83/215,748 - 35/16 = ? Feb 22 10:22 UTC (GMT) 75/100 - 25/100 = ? Feb 22 10:22 UTC (GMT) 1,800 - 1/3 = ? Feb 22 10:22 UTC (GMT) see more... subtracted fractions

## How to: Subtracting ordinary (simple, common) math fractions. Steps.

There are two cases regarding the denominators when we subtract ordinary fractions:

• A. the fractions have like denominators;
• B. the fractions have unlike denominators.

### A. How to subtract ordinary fractions that have like denominators?

• Simply subtract the numerators of the fractions.
• The denominator of the resulting fraction will be the common denominator of the fractions.
• Reduce the resulting fraction.

### An example of subtracting ordinary fractions that have like denominators, with explanations

• #### 3/18 + 4/18 - 5/18 = (3 + 4 - 5)/18 = 2/18;

• We simply subtracted the numerators of the fractions: 3 + 4 - 5 = 2;
• The denominator of the resulting fraction is: 18;

### B. To subtract fractions with different denominators (unlike denominators), build up the fractions to the same denominator. How is it done?

• #### 1. Reduce the fractions to the lowest terms (simplify them).

• Factor the numerator and the denominator of each fraction, break them down to prime factors (run their prime factorization).
• #### Factor numbers online, break them down to their prime factors.

• Calculate GCF, the greatest common factor of the numerator and of the denominator of each fraction.
• GCF is the product of all the unique common prime factors of the numerator and of the denominator, multiplied by the lowest exponents.
• #### Calculate the greatest common factor, GCF, online.

• Divide the numerator and the denominator of each fraction by their GCF - after this operation the fraction is reduced to its lowest terms equivalent.

• #### 2. Calculate the least common multiple, LCM, of all the fractions' new denominators:

• LCM is going to be the common denominator of the added fractions, also called the lowest common denominator (the least common denominator).
• Factor all the new denominators of the reduced fractions (run the prime factorization).
• The least common multiple, LCM, is the product of all the unique prime factors of the denominators, multiplied by the largest exponents.

• #### 3. Calculate each fraction's expanding number:

• The expanding number is the non-zero number that will be used to multiply both the numerator and the denominator of each fraction, in order to build all the fractions up to the same common denominator.
• Divide the least common multiple, LCM, calculated above, by the denominator of each fraction, in order to calculate each fraction's expanding number.
• #### 4. Expand each fraction:

• Multiply each fraction's both numerator and denominator by the expanding number.
• At this point, fractions are built up to the same denominator.
• #### 5. Subtract the fractions:

• In order to subtract all the fractions simply subtract all the fractions' numerators.
• The end fraction will have as a denominator the least common multiple, LCM, calculated above.