ORDER OF OPERATIONS When doing a calculation it is important to do operations, such as addition and multiplication, in the correct order. For example, if you purchased 2 books at $20 each and 3 magazines at $3 each you, would calculate the total amount spent by, first of all calculating the total cost of the books, then calculating the total cost of the magazines and finally adding these two totals together. (2 $20) + (3 $3) = $40 + $9 = $49 Namely you would do the two multiplications first before adding the results. This leads us to see that you would perform multiplications and divisions before additions and subtractions. There is a common pneumonic, which is easy to remember, for the order in which to perform operations. B E D M A S BRACKETS ADDITION SUBTRACTION same order of precedence work from left to right EXPONENT OR POWER DIVISION MULTIPLICATION same order of precedence work from left to right In any calculations that you perform, you would action operations that lie in brackets first, then you would calculate an exponent (or power), next you would either multiply or divide and finally you would perform additions or subtractions. 7 (4 + 1) - 5 3 = 7 5 - 5 3 = 35 - 15 = 20 (4 – 1)2 8 - 2 = 32 8 - 2 = 9 8 - 2 = 72 - 2 = 70 1 Updated March 2013 Order of operations exercises A Calculate 1. 6 + 2 9 2. 15 - 3 2 3. 13 - 6 2 4. 42 2 + 7 5. 17 - 3 5 6. (7 - 3) 5 7. 5 3 - 4 2 8. 8 + 2 9 + 4 9. (11 - 9) 10 + 7 3 10. 24 + (3 4) 6 11. 18 (21 - 9 2) 12. 3 + 42 - 7 13. 5 (3 + 2) - 4 5 14. (31 + 7 3) 4 15. [12 - (7 - 2)] (6 + 3) 16. 3 (9 - 4) - 2 (1 + 4) 17. (6 – 2) 20 + 7 3 18. 22 + [(4 + 5) 3] 19. 3 (6 + 1) - 14 2 20. 50 - 18 (13 – 11) 4 21. 32 8 12 3 22. 25 (7 – 2) + 5 3 23. 4 12 - 32 + 5 - (3 + 5) (8 – 2) B Put in brackets where necessary to make each of the following statements true. 1. 4 + 5 - 2 = 7 2. 16 - 9 2 = 14 3. 7 + 4 9 - 3 = 66 4. 7 + 4 9 - 3 = 40 5. 5 + 1 0 = 0 6. 5 + 1 0 = 5 7. 72 8 - 3 + 1 = 7 8. 72 8 - 3 + 1 = 5 9. 21 5 - 3 - 5 + 6 = 31 10. 24 4 3 + 2 = 30 11. 16 - 7 + 4 - 1 = 4 12. 200 20 + 20 = 5 13. 12 + 8 - 5 - 1 = 16 14. 12 + 8 - 5 - 1 = 14 2 Updated March 2013 Order of operations exercises solutions A 1. 24 3. 10 2. 9 4. 28 5. 2 6. 20 7. 7 8. 30 9. 41 10. 26 11. 6 12. 12 13. 5 14. 13 15. 63 16. 5 17. 101 18. 49 19. 14 20. 41 21. 16 22. 20 23. -27 B 1. 4 + 5 - 2 = 7 2. (16 - 9) 2 = 14 3. (7 + 4) (9 - 3) = 66 4. 7 + (4 9 - 3) = 40 5. (5 + 1) 0 = 0 6. 5 + 1 0 = 5 7. 72 8 - 3 + 1 = 7 8. 72 8 - (3 + 1) = 5 9. 21 (5 - 3) - (5 + 6) = 31 10. 24 4 (3 + 2) = 30 11. 16 - (7 + 4) - 1 = 4 12. 200 (20 + 20) = 5 13. 12 + 8 - (5 - 1) = 16 14. 12 + (8 - 5) - 1 = 14 3 Updated March 2013