Securing good value purchases at the supermarket can assist with trimming costs on groceries, and there’s a straightforward method to ensure you understand exactly how much you’re saving.

Everything revolves around percentages, with numerous offers available including 25% reductions, buy-one-get-one-at-half-price and other similar promotions.

If you can calculate individual offers rapidly while shopping, you can establish the benefit gained from accepting them.

Lyndsey Hartley, mathematics department head at Kelvinside Academy, considers that mastering mental percentage calculations constitutes one of the most practical skills anyone will employ throughout their lifetime.

Methods for confirming you’re obtaining worthwhile supermarket offers

For optimal assessment of supermarket offer worth, Lyndsey suggests first establishing what 10% of the cost represents.

This approach works because the figure can be divided or multiplied to reach any required percentage.

She stated that for items priced at £10, or any sum ending in zero, you simply drop the final digit.

10% of £10 equals £1.

10% of £50 equals £5.

10% of £100 equals £10.

When dealing with amounts not ending in zero, you simply shift the decimal point one position left.

10% of £15 equals £1.50.

10% of £55 equals £5.50.

10% of £105 equals £10.50.

Once you’ve determined 10%, calculations become straightforward. For 5%, take half of the 10% figure. For 20%, double the 10% amount.

This technique proves valuable for rapidly assessing supermarket promotions, such as those offering 25% off.

Lyndsey continued by demonstrating with an £8 product reduced by 25%. Begin with 10%, which equals 80p. Double this for 20% to get £1.60, then add half of that amount again to reach £2. The final cost becomes £6.

Buy-one-get-one-half-price offers can similarly be computed swiftly.

She illustrated that when one item costs £6, the second at half price brings the total to £9. This works out as £4.50 per item, meaning genuine savings only occur if both products are actually required.

Promotions advertising 25% extra free can also be verified instantly.

Lyndsey clarified that for 8 rolls, 25% represents a quarter, which adds two more, giving 10 rolls in total.

One consideration when calculating supermarket value

As an additional recommendation for evaluating supermarket offers, Lyndsey proposes applying the £1 guideline.

She noted that allowing yourself a margin of error within £1 immediately reduces the pressure considerably. The key point is that this isn’t an examination situation, merely a quick sanity check, and this relaxed approach makes people considerably more inclined to attempt the calculations.