 # Multiplying Fractions

Multiplying Fractions:

THIS IS A LONG PAGE, SCROLL DOWN WHEN READING TO SEE IT ALL.

COPY THESE STEPS INTO YOUR NOTES OR PUT THEM ON A PIECE OF PAPER.

Part 1: Beginning to multply simple fractions:

Step One: Simplify diagonally,  look at opposite corners  and simpilfy numbers down to where the only factor they have in common is 1 . Cross out and rename as you work.

3                   5

__      X      __

15               12

1          5   1           We divide both 5 and 15 by 5 to get new numbers

___   X   ___

15  3         12   4          We divide both 3 and 12 by 3 to get new numbers.

Step 2:   Now that we have simplified as much as possible, we multiply the new numbers straight across.

3   1            5   1                          1

___   X   ___             =         _____

15  3         12   4                        12

If the answer is not fully simplified, we would simplify it again.

Part 2:  Simplifying before multiplying with similar numbers cancel out.

2             5

__    X  ___

5              15

2                 5    1           You can simplify similar diagonal numbers, they cancel out and are rewritten as 1's

__     X      ___

5    1         15

2                 5    1                    2

__     X      ___          =    _____

5    1         15                        15

If the answer is not fully simplified, we would simplify it again.

PART 3: An example for simplification still needed after simplifying diagonally and multiplying:

2           2                 Simplify         2              2    1                  2                   1

__  x  ___                                  ___     X  ____        =   _____    =   _____

8           5                                     8    4               5                    20                  10

We simplified our first answer 2/20 because they were even and still had a greatest common factor other than the number 1.

Use all the rules for simplifying you have been taught.

Part 4: Some problems can not be simplified diagonally or cancel out. In these cases, multiply straight across. Remember to simplify final answer as needed.

Part 5: Whole number are wrote over 1 and to create a fraction to multiply with another fraction:

Example -- 8 X  1/2   would be wrote as        8        1

__   X   ___

1           2               and the complete the problem as usual.

STOP TAKING NOTES! You have finished the notes, save them, use them, treasure them!

Assignment: Click on the link, scroll down to "Practice" section, click on "Start" in yellow, copy the problems down setting them up as in the notes. Then simplify, or cancel out numbers before multiplying straight across, you can neatly do this on the problems you copy down.

Here is an example:     3/10  *  4/5                     3                   4    2              6

___     X       ___         =   ____

10   5            5                   25

DO NOT COMPLETE THESE PROBLEMS IN YOUR HEAD. YOU MUST COPY THEM DOWN, COMPLETE THE PROCESS OF SOLVING ON PAPER, AND TURN THE PAPER IN. I WILL ALLOW ADDITIONAL CLASS TIME TO FINISH THE ASSIGNMENT IN OTHER CLASSES AS NEEDED.

Multiplying Fraction Games: