Free Maths Calculator

Best Buy Calculator

Two packs, two prices, one honest answer. Enter both deals and the calculator works out the price per unit for each, names the better buy, and shows the saving. Best buy questions are pure division, but only once both prices are measured on the same scale, which is the whole method.

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    Worked Example

    300 g of coffee costs £2.40. A 200 g jar costs £1.80. Which is the better buy?

    1. Price per 100 g for the big jar:2.40 ÷ 300 × 100 = £0.80
    2. Price per 100 g for the small jar:1.80 ÷ 200 × 100 = £0.90
    3. Compare: 80p beats 90p per 100 g, so the 300 g jar is the better buy

    Answer: The 300 g jar (80p per 100 g vs 90p)

    Try These Yourself

    5 pens for £3.00 or 8 pens for £4.40. Which is better value?Show answerHide answer

    Answer: 8 pens

    60p each against 55p each.

    250 ml for £1.25 or 400 ml for £1.90. Better buy?Show answerHide answer

    Answer: 400 ml

    50p per 100 ml against 47.5p per 100 ml.