Do We Need a 37-Cent Coin? (2009)

Optimal coin denominations

• Original article’s 1–3–11–37 system optimizes the greedy algorithm but isn’t globally optimal.
• Multiple commenters cite work showing 1–5–18–25 and 1–5–18–29 minimize average coins per transaction more effectively.
• Some propose alternative sets (e.g., 1–3–10–25; powers of 2) and note that better mathematical efficiency may increase mental overhead when making change.
• Debate over whether a 1‑cent coin is “always necessary”; one suggestion is dropping it and using only primes (2,5, …) plus change-back rules.
• A linked theoretical CS discussion addresses asymptotic behavior of coin-changing; status of that result is unclear in the thread.

Eliminating low-value coins & rounding

• Many argue the penny (and sometimes nickel/dime) should be abolished; value is too low and minting can cost more than face value.
• Examples: Canada, Netherlands, Denmark, Sweden, Australia round cash transactions (typically to 0.05 or 1 unit), while electronic transactions remain exact.
• Some fear rounding is a hidden price increase; others note strict rounding rules and that typical gain/loss per purchase is only a few cents.
• Several think inflation will eventually make all sub‑dollar coins pointless, with transactions rounded to whole dollars.

Pricing, taxes, and .99 endings

• .99 pricing is widely criticized; some want it banned or normalized (e.g., quarters only, tax-included prices).
• US practice of listing prices pre‑sales‑tax is contrasted with VAT‑inclusive pricing in the UK/EU; pre‑tax .99 plus tax creates messy, unpredictable totals.
• There’s disagreement on why .99 emerged (anti-theft vs. psychological pricing), and its rationale under modern sales tax is questioned.
• The ubiquitous “x.9/10 cents” on US gasoline is mocked; one link attributes it to tax law.

Metric vs imperial and consumer math

• The coin discussion spills into unit systems: metric is seen as simpler for comparisons, while imperial/US customary allows confusing package sizes.
• Some argue the main barrier to metric adoption is transition cost and lack of benefit for currently-competent adults.
• Others find US supermarket units and arbitrary “serving sizes” make value comparison needlessly hard; EU-style standardization is praised.

Coins vs bills, design, and usage

• Mixed views on replacing small bills with coins: coins are more durable but heavier and harder to carry; bills (especially modern polymer) are lightweight and pleasant.
• Some countries’ coins (e.g., UK) are praised for clear size/shape/color differentiation; Euro and Scandinavian coins are seen by some as too similar, by others as well-designed for the blind.
• Jokes suggest very high‑denomination coins or rare‑metal coins; critics note such designs could encourage hoarding or melting for metal value.
• Several people barely use cash at all; coins accumulate in jars or are used only for niche cases (parking, carts).

Cash vs electronic payments and fees

• One side claims cash-handling (errors, theft, counting, bank trips) can cost more than card fees; another small-business operator says cash is still cheaper than 2–3% card fees, given modest handling time.
• Rounding-up charity requests at checkout are debated; clarification that in typical US law, corporations don’t get a tax deduction windfall from customers’ donations, but they do gain marketing benefits.
• Some see the shift to cards/apps as making coin optimization moot; others still value efficient, simple physical cash systems.