Money and best buys

Pay is often an hourly rate × hours worked. Overtime is extra hours paid at a higher rate, such as "time and a half" (1.5 × the normal rate).

1. Work out the basic pay.
2. Work out the overtime rate and the overtime pay.
3. Add them.

Example: Jo earns £12.40 an hour. One week she works 37.5 hours, plus 6 hours of overtime at time and a half. How much does she earn?

1. Basic: 37.5 × 12.40 = £465
2. Overtime rate: 1.5 × 12.40 = £18.60, so 6 × 18.60 = £111.60
3. Total: 465 + 111.60 = £576.60

Many prices have VAT (20%) added, and bills often add a fixed standing charge to a cost per unit.

Example: a phone costs £85 before VAT. Find the price with 20% VAT.

1. Multiplier: 1.2
2. 85 × 1.2 = £102

Example: an electricity bill has a standing charge of 45p a day for 90 days, plus 1200 units at 28p each. Find the total.

1. Standing charge: 90 × 0.45 = £40.50
2. Units: 1200 × 0.28 = £336
3. Total: 40.50 + 336 = £376.50

Change pence to pounds before adding, so every amount is in the same unit.

An exchange rate tells you how much one currency is worth in another, such as £1 = €1.15.

• To change pounds to euros, multiply by the rate.
• To change euros to pounds, divide by the rate.

Example: £1 = €1.15. Change £200 to euros, and €345 to pounds.

1. £200 × 1.15 = €230
2. €345 ÷ 1.15 = £300

Check that the answer makes sense: euros are worth less than pounds here, so there should be more euros than pounds.

To find the best buy, compare the same amount of each: the cost per unit (lower is better) or the amount per pound (higher is better).

1. Pick a unit both sizes divide into, such as 100 g.
2. Work out the cost of that unit for each size.
3. Choose the cheapest, and say why.

Example: which is better value: 500 g of cereal for £1.80, or 750 g for £2.55?

1. 500 g: £1.80 ÷ 5 = 36p per 100 g
2. 750 g: £2.55 ÷ 7.5 = 34p per 100 g
3. The 750 g box, because it costs less per 100 g