Try some yourself
Activity 62
Give examples of all the rules for the division of and by positive and negative numbers.
Answer
Your list should look something like this.
Dividing a positive number by a positive number gives a positive answer.
4 ÷ 2 = 2.
Dividing a negative number by a positive number gives a negative answer.
−4 ÷ 2 = −2.
Dividing a positive number by a negative number gives a negative answer.
4 ÷ −2 = −2.
Dividing a negative number by a negative number gives a positive answer.
−4 ÷ −2 = 2.
Activity 63
Evaluate each of the following and where possible give an example from everyday life to illustrate the calculation.
(a) 24 ÷ −4
(b) −40 ÷ −4
(c) −45 ÷ 15
Answer
(a) 24 ÷ −4 = −6
Thomas has lots of £4 IOUs. A gift of £24 will subtract 6 of them.
(b) −40 ÷ −4 = 10
An IOU of £40 divided into smaller IOUs of £4 each (which could be paid off more easily from Thomas’s pocket money) gives 10 smaller IOUs.
(c) −45 ÷ 15 = −3
A debt of £45 shared between 15 people means each owes £3.
Activity 64
Evaluate each of the following.
(a) 7 × −6
(b) −56 ÷ −7
Think of a financial context where each might be an appropriate calculation (bear in mind that negative numbers can represent debts).
Answer
(a) 7 × −6 = −42
(7 debts of £6 result in a debt of £42).
(b) −56 ÷ −7 = 8
(a £56 debt divided into £7 debts gives eight £7 debts).
If you have a calculator check that it gives the same answers as yours.
OpenLearn - Numbers, units and arithmetic
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