If possible without calculating: Tell whether the fraction is a lowest terms fraction.

Simplify (or reduce) a fraction by dividing both the *numerator* and the *denominator* by the simplification number.

A lowest terms fraction can not be simplified further.

If you would like to have a vivid explanation with a detailed example, please read the page Simplifying/Reducing Fractions - Learn this magic trick!

**Step 1: Test, if the numerator or the denominator is equal to 1.**

If the numerator or the denominator is equal to 1, the fraction is simplified to lowest terms.

Since this is not the case, go on to the next test:

**Step 2: Test, if the numerator or the denominator is a prime number**

If the numerator or the denominator is a prime number and they are **not multiples**, the fraction is simplified to lowest terms!

In this case, whether the numerator nor the denominator is a prime number. Go on to the next test:

**Step 3: Test, if the numerator and the denominator both are divisible by 10, 5 or 2**

You can see from the last digit, if a number is divisible by 10, 5 or 2.

The fraction can not be simplified by 10, 5 or 2. Go on to the next test:

**Step 4: Test, if the numerator and the denominator both are divisible by 3 or 9**

Calculate the *cross sum* of the numerator and the cross sum of the denominator:

Numerator: 1 + 8 = 9

Denominator: 1 + 5 = 6

The cross sums are both divisible by 3.

The fraction can be simplified further, namely the number 3.