Smart Shopping Math: Unit Prices, Pack Sizes, Multi-Buy Offers, Coupons and a Personal Price Book

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn nine shelf prices into comparable unit prices, round them like a shelf label, and find the cheapest olive oil by value and by name with MINIFS and INDEX/MATCH.
• Compare each pack with the next smaller one of the same product, measure how much cheaper per kg it is, flag the packs that break the rule and count the exceptions.
• Turn three kinds of multi-buy offers into one model, work out the effective price per item, the cost for exactly the quantity Lena needs with INT and MOD, the cost of topping up to full groups and the saving on the whole list.
• Check how long each pack lasts at Lena's real use, how much of it she uses within her planning horizon, what share is left over and what each 100 g or ml she actually uses really costs.
• Apply a capped percent coupon and a fixed coupon with a minimum spend in the shop's order, then add loyalty points and capped cashback to find what Lena's weekly and monthly shops really cost.
• Follow three products over two and a half years, separate the change on the price tag from the change in the unit price, turn the total rise into a rate per year with DAYS and POWER and name the product with the biggest hidden rise.
• Keep a price book of six items at three shops, find the cheapest price per item with MINIFS, total the monthly basket per shop with SUMIF or SUMPRODUCT, price the split basket and decide whether the extra trips are worth it.
• Turn Lena's October receipts into a dashboard: the saving per receipt line, regular price, paid and saving per category with SUMIFS, the overall saving rate and a column chart of the savings by category.