Today in math we reviewed for the test on GCF (greatest common factor), LCM ( least common multiple), adding, subtracting, dividing, and multiplying fractions and mixed numbers.

To find the greatest common factor of two numbers you figure out the prime factorization for each number. For example: 40 and 60.

40- 2*2*2*5

60- 2*2*3*5

then you find all of the factors that the two numbers have in common.

2 2 and 5 so the GFC is- 2*2*5 or 20

To find the least common you...

1. write the prime factorization

2. Use the greatest power of each factor

3. Write the LCM as a product

For example: 12 and 8

STEP 1

12- 2*2*3 =

8- 2*2*2- 2

STEP 2

2 to the second power * 3

2 to the third power ARE = TO 2 TO THE THIRD POWER *3

STEP3

two to the third power * 3 =

8* 3= 24

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To add fractions you have to find a common denominator. For example: 1/2 + 3/4=?

To find the common denominator you could multiply both denominators. Or you could divide the

denominators. In this case 2 goes into 4 evenly so the new fractions would be: 2/4 + 3/4=? Now

you add across but keep the denominator the same. so the answer is 5/4 or 1 1/4.

The same thing applies for subtracting fractions.

To multiply fractions all you do is multiply across.

To divide fractions, you keep the first fraction the same and flip the second upside down. For

example: 3/5 divided by 3/4, you keep the first fraction and change the second on to its

reciprocal 4/3 and change the division sign into a multiplication sign.

To add mixed numbers you do the same thing, find the common denominator and add the

add the fractions and then the whole numbers. Simplify if possible.

Do the same to subtract.

To multiply change the numbers into improper fractions, multiply across and then simplify.

Example-2 3/4 * 1 1/5 = 11/4 * 6/5= 66/2o= 33/10= 3 3/10

To divide change the mixed numbers into improper fractions. Then keep the first the same and

change the second one to its reciprocal. change the division sign to a multiplication sign.

Then simplify.

3 1/4 divided by 1 1/2= 13/4 divided by 3/2= 13/4 * 2/3=26/12= 2 1/4

=D =P =] =O