1.4 BEDMAS
Fortunately, there is an easy way to remember the correct order in which arithmetic operations should be carried out. The rules are neatly summed up in the mnemonic BEDMAS. The letters in BEDMAS stand for Brackets, Exponents, Division, Multiplication, Addition and Subtraction, and the order of the letters gives the order in which the operations should be carried out. In other words, you should work out the brackets first, then the exponents (otherwise known as indices or powers), then any divisions and multiplications, and finally the additions and subtractions. You may see BIDMAS (where the ‘I’ stands for ‘Indices’) or BODMAS written instead of BEDMAS; the three expressions are equivalent.
There is one final point to make about the order in which arithmetic should be done. When faced with a calculation that includes a series of multiplications and divisions (or a series of additions and subtractions), then you should work through the calculation from left to right in the order in which it is written.
Question 1.4
To practise the BEDMAS rules, try the following calculations both in your head and with your calculator.
- a.
Working from left to right gives
- b.
The multiplication should be done before the addition, so
- c.
The bracket should be evaluated first, so
- d.
The multiplication should be done before the subtraction, so
- e.
The bracket should be evaluated first, so
- f.
Working from left to right gives
- g.
The bracket should be evaluated first, so
- h.
The bracket should be evaluated first, so
- i.
The term including an exponent, 32, should be evaluated first, so
- j.
The innermost brackets should be evaluated first, so