Transcription of ADDING, SUBTRACTING, MULTIPLYING, AND DIVIDING …
1 1 WJEC MATHEMATICS INTERMEDIATE fractions , DECIMALS, AND PERCENTAGES adding , subtracting , multiplying , AND DIVIDING fractions 2 Contents multiplying fractions DIVIDING fractions adding fractions subtracting fractions Credits WJEC Question bank 3 multiplying fractions In order to multiply fractions , multiply the numerators and multiply the denominators 25 37 = 635 Exercise N50a. 23 14 b. 34 811 c. 49 16 d. 38 512 e. 79 45 f. 211 56 g. 512 711 h. (34)2 i. 413 245 DIVIDING fractions When DIVIDING fractions , use the KFC method So, using this method 18 12 becomes 18 21=28=14 KFC (Keep-Flip-Change) Method: K - Keep the first fraction the same.
2 F - Flip the second fraction C - Change the sign to a 4 Exercise N51 Calculate: a. 23 57 b. 34 25 c. 45 13 d. 47 34 e. 56 25 f. 34 29 g. 712 1320 h. 58 1316 i. 423 357 adding and subtracting fractions Method 1 The first method for adding and subtracting is to get the denominators of both fractions the same (See the booklet 'Equivalent fractions ') Example 25+310 We can write this question using equivalent fractions 410+310 So we have four tenths and we add an another three tenths. So we have seven tenths all together. Add the numerators, not the denominators! 410+310=710 5 Method 2 This is the method you need to use when you are unable to use equivalent fractions .
3 To help remember this method, consider the following Cha Cha Slide lyrics So, here's how it works! Consider this example 25+27 First, we slide to the left. This means multiplying the bottom right by the top left. 25+27= 14+[ ][ ] Next, we slide to the right. This means multiplying the bottom left by the top right. 25+27= 14+10[ ] Finally, we criss-across the bottom. This means multiplying the bottom two numbers. 25+27= 14+1035 14+1035=2435 Slide to the left Slide to the right Criss-cross! Check it out on YouTube if you haven't heard of it! It's catchy! 6 Note: The method for addition and subtraction is the same.
4 The only difference is the sign you include in your answer. Here is a subtraction example. 35 29 First, we slide to the left. This means multiplying the bottom right by the top left. 35 29= 27 [ ][ ] Next, we slide to the right. This means multiplying the bottom left by the top right. 35 29= 27 10[ ] Finally, we criss-across the bottom. This means multiplying the bottom two numbers. 35 29= 27 1045 27 1045=1745 Exercise N52a. 34+ 28 b. 29+ 218 c. 37 114 d. 58 724 e. 34 13 f. 59 27 g. 67 35 h. 56 19 i. 34+ 23 j. 29+ 25 k. 37+ 14 l. 58+ 79 7 Exam Question N28 1. 2. 3. 4. 5.
