The idea of **getting the least common multiple **of the denominator in** adding dissimilar fractions** is to convert them into similar fractions or fractions whose denominators are the same. Once the fractions are similar, you only need to add the numerator and copy the denominator.

The solutions to **Fraction Addition Practice Test 1** below is divided into three parts: (1) getting the least common multiple of the denominator, (2) converting the given fractions to their equivalent fractions whose denominator is the LCM and (3) adding the converted fractions. Of course, in solving this types of problem the Civil Service Exam, you don’t need to go through all the steps. You should try developing your own short cuts to make solving faster.

**Solution and Answers to the** **Fraction Addition Practice Test 1**

**Solution to Number 1**

Given:

Answer:

**Solution to Number 2**

Given:

Answer:

**Solution to Number 3**

Given:

*A. Get the LCM of the denominators 8 and 3.*

Multiples of 3: 3, 6, 9, 12, 15, 18, **24**

Multiples of 8: 8, 16, **24**, 32, 40

Therefore, the LCM of 8 and 3 is **24**.

*B. **Convert* *the given** to equivalent fractions whose denominator is 24.*

( which results to .)

( which results to .)

So, and

*C. Add the fractions.*

Answer: .

**Solution to Number 4**

Given:

*A. Get the LCM of 4, 2, and 5. *

Multiples of 2: 2, 4, 6, 8, 10, 12, 14, 16, 18, **20**, 22

Multiples of 4: 4, 8, 12, 16, **20**, 24

Multiples of 5: 5, 10, 15, **20**, 25

*B. **Convert* *the given** to equivalent fractions whose denominator is 20.*

( which results to .)

( which results to .)

( which results to .)

So, , and .

*C. Add the fractions.*

Answer: or

**Solution to Number 5**

Given:

*A. Get the LCM of the denominators 6 and 3.*

Since 6 is divisible by 3, the LCM of 6 and 3 is **6**.

*B. **Convert* *the given** to equivalent fractions whose denominator is 6.*

Since has already denominator 6, we only need to convert .

( which results to ).

So, .

*C. Add the equivalent fractions*

Answer: .

**Solution to Number 6**

Given:

*A. Get the LCM of the denominators 4 and 8.*

Since 8 is divisible by 4, the LCM of 4 and 8 is **8**.

*B. Convert the given to equivalent fractions whose denominator is 8.*

Since has already 8 as denominator, we only need to convert .

. ( which results to ).

So, .

*C. Add the fractions. *

Answer:

**Solution to Number 7**

Given:

*A. Get the LCM of the denominators 2, 3, and 6.*

Six are both divisible by 2 and 3, sLCM of 2, 3, and 6 is **6**.

*B. Convert the given to equivalent fractions whose denominator is 6.*

We only need to convert and .

( which results to ).

( which results to ).

So, and .

*C. Add the fractions.*

Answer: or

**Solution to Number 8**

Given:

Answer:

**Solution to Number 9**

Given: .

*A. Get the LCM of the denominators 3 and 9.*

Since 9 is divisible by 3, the LCM of 3 and 9 is **9**.

*B. Convert the given to equivalent fractions whose denominator is 9.*

We only need to convert .

( which results to ).

*C. Add the fractions.*

.

Answer: or in lowest terms.

**Solution to Number 10**

Given:

*A. Get the LCM of the denominators 8, 2, and 3.*

Multiples of 2: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, **24**, 26

Multiples of 3: 3, 6, 9, 12, 15, 18, 21, **24**, 27, 30

Multiples of 8: 8, 16, **24**, 32, 40

So, the LCM of 8, 2 and 3 is **24**.

*B. Convert the given to equivalent fractions whose denominator is 8.*

( which results to .)

( which results to .)

( which results to .)

So, , and .

*C. Add the fractions.*

.

Answer:

**Solution to Number 11**

Given:

*A. Get the LCM of the denominators 7 and 21.*

Since 21 is divisible by 7, the least common multiple of 7 and 21 is **21**.

*B. Convert the given to equivalent fractions whose denominator is 21.*

We only need to convert .

: ( which gives .)

So, .

*C. Add the fractions.*

Answer:

**Solution to Number 12**

Given:

*A. Get the LCM of the denominators 2, 3, and 10.*

Multiples of 2: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, **30**, 32

Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, **30**, 33

Multiples of 10: 10, 20, **30**, 40, 50

The LCM of 2, 3, and 10 is **30**.

*B. Convert the given to equivalent fractions whose denominator is 30.*

( which results to .)

( which results to .)

( which results to .)

So, , and .

*C. Add the fractions.*

Answer: or or in lowest terms.

**Solution to Number 13**

Given:

*A. Get the LCM of the denominators 8, 5, and 2.*

Multiples of 2: 2, 4, 6, 8, 10, …, 36, 38, **40**, 42

Multiples of 5: 5, 10, 15, 20, 25, 30, 35, **40**, 45, 50

Multiples of 8: 8, 16, 24, 32, **40**, 48, 56

So, the LCM of 8, 5, and 2 is **40**.

*B. Convert the given to equivalent fractions whose denominator is 40.*

( which results to .)

( which results to .)

( which results to .)

So, , and .

*C. Add the fractions.*

Answer: or

**Solution to Number 14**

Given:

*A. Get the LCM of the denominators 3, 9, and 6.*

Multiples of 3: 3, 6, 9, 12, **18**, 21

Multiples of 6: 6, 12, **18**, 24, 30

Multiples of 9: 9, **18**, 27, 36, 45

So, the LCM of 3, 9 and 6 is **18**.

*B. Convert the given to equivalent fractions whose denominator is 18.*

( which results to .)

( which results to .)

( which results to .)

So, , and .

*C. Add the fractions.*

14.

Answer:

**Solution to Number 15**

Given:

*A. Get the LCM of the denominators 4, 3 and 6.*

Multiples of 4: 4, 8, **12**, 16, 20

Multiples of 3: 3, 6, 9, **12**, 15

Multiples of 6: 6, **12**, 18, 24, 30

So, the LCM of 4, 3, and 6 is **12**.

*B. Convert the given to equivalent fractions whose denominator is 8.*

( which results to .)

( which results to .)

( which results to .)

So, , and .

*C. Add the fractions.*

Answer: or

This is a very long post so please inform me if you have spotted any errors in the solutions.

Thanks for the reviewer

thanks a lot it’s very helpful:) do you have a vocabulary in english and filipino?

Hi Mark. I have English vocabulary, but no Filipino yet. Please, check out the English page above. 🙂

Got it all!100%! Thank you for meticulously explaining the process…

Yes, the answer is 10/21. Typo error. I already changed it. Thank you.

the given was 1/7 + 2/21. so the answer must be 3/21+2/21=5/21 right?

Given problem in number 11 is 1/7 + 2/21 but you solve this problem with 7/21 instead of 2/21

Fixed it already.

1/4=x/12

X= (12÷4)x1= 3 po. Sol no.15 po.