FRACTIONS COMMON MISTAKES

Transcription

1 FRACTIONS COMMON MISTAKES 0/0/009

2 Fractions Changing Fractions to Decimals How to Change Fractions to Decimals To change fractions to decimals, you need to divide the numerator (top number) by the denominator (bottom number). To View the document, select ctrl and double click the link Dividing the denominator by the numerator. Incorrect: Correct: Therefore, Note: Be careful to divide top number by bottom number. 0.

3 Fractions - Reducing How to Reduce Fractions To reduce fractions divide the largest common number into both the numerator (the top) and the denominator (the bottom). Not reducing the fraction all the way. Incorrect Correct 0/0/009

4 Fractions, Mixed Numbers How to create a mixed number. To make a mixed number, the numerator must be larger than the denominator. Divide the denominator (the bottom) into the numerator (the top), the number of times it goes is the whole number. The remainder goes in the numerator. 0 Example: Seven goes into 0 once, with left over So 0 Trying to make a mixed number when the numerator (the top) is smaller than the denominator (the bottom) This cannot be made into a mixed number 0 0/0/009

5 Fractions Lowest Common Denominator How to find the LCD Write the multiples of all the denominators. Ex. The denominators are and. Multiples of :,,,,0, Multiples of :,, 9, Select the smallest common number. The LCD is Write equivalent fractions Not finding the smallest LCD Finding a number that goes into both of the denominators, NOT a number that both denominators go into. Ex. Incorrect: In the example above, will go into both and ; so students will use an LCD of for the problem. Correct: 9 In the example above, the LCD is. 0/0/009

6 Fractions Adding and Subtracting How to add and Subtract Fractions Make sure the fractions have a common denominator. (see slide ) Not finding a common denominator Add or Subtract the numerator. Reduce the fraction Adding/subtracting both the numerator and denominator. Incorrect Correct 9 Note: You can t ever add or subtract the denominators. 0/0/009

7 Fractions - Multiplying How to Multiply Fractions To multiply fractions, multiply each of the numerators (the top numbers) together and each of the denominators (the bottom numbers) together. Reducing can be done before the multiplying or after the products are found. Trying to find the Least Common Denominator before multiplying. Not reducing the product all the way. Incorrect: Correct: Note: You do NOT need a Common Denominator to multiply fractions. 0/0/009

8 Fractions - Dividing How to Divide Fractions Take the fraction following the division sign and flip it - take the reciprocal. Multiply the fractions Hint: You must cancel after you have flipped the fraction. Ex. Canceling before you flip. Incorrect: By canceling the from the first fraction into the in the second fraction the answer comes out wrong. Correct: In this example, the canceling was done after the fraction was flipped, thereby giving the correct solution. Forgetting to flip the fraction following the division sign. Forgetting to reduce the final answer. Flipping (taking the reciprocal) of both fractions 0/0/009