2.2 Rounding to approximate an answer
You might round in order to approximate an answer. At the coffee shop, you might want to buy a latte for £2.85, a cappuccino for £1.99 and a tea for £0.99. It is natural to round these amounts up to £3, £2 and £1 in order to arrive at an approximate cost of £6 for all three drinks.
Activity 4: Approximation
Find an approximate answer to each of the following:
Cost of 3 kg of child friendly glue at 79p per kg.
The total cost of 3 story books at £1.99, £2.85 and £4.90.
Change from a £20 note when £3.84 has been spent.
Approximate cost of one carton of fruit juice when a pack of 4 are sold together for 99p.
Approximate cost: 3 × 80p = 240p = £2.40
Approximate cost: £2 + £3 + £5 = £10
Approximate change: £20 − £4 = £16
Approximate cost of one carton: 100p ÷ 4 = 25p