The interactive uses the invented Day 11 data only. It does not send or store input. This page contains the same prices, rule, worked challenge cases and claim boundary, so no device, sound, fine-motor mouse control or network is required.
Data: Set S = 25 cards for $20. Set L = 50 cards for $35. Buy whole sets only; mixed S/L purchases are allowed. Delivery is unknown. Cards are assumed identical for the teaching model. A lower per-card price is not automatically a lower purchase outlay for a stated need.
Method: 1. State the number of cards needed. 2. Calculate S-only: round the needed cards up to a whole count of 25-card sets, then multiply by $20. 3. Calculate L-only the same way for 50-card sets at $35. 4. Try mixed nonnegative whole counts of S and L that cover at least the need; compare stated cash outlays. 5. Give the least stated outlay for that quantity only. 6. Keep delivery in UNKNOWN; do not call it free.
| Needed | S-only | L-only | Least stated whole-set mix |
|---|---|---|---|
| 20 | 1 S = $20 |
1 L = $35 |
1 S = $20 |
| 40 | 2 S = $40 |
1 L = $35 |
1 L = $35 |
| 75 | 3 S = $60 |
2 L = $70 |
1 S + 1 L = $55 |
Unit-price side check: S $20÷25=$0.80/card; L $35÷50=$0.70/card. The exact quantities show why the public word any is unsupported. At 20, S costs $15 less in stated whole-set cash; at 40, L costs $5 less; at 75, the mixed route beats either single-set-type route. Unused cards are counted in the paid whole set.
Tactile route: Make raised-edge cards labelled S · 25 cards · $20, L · 50 cards · $35, NEED and UNKNOWN DELIVERY in Braille/large text/speech as appropriate. Place enough complete S/L cards to reach each need. Add the visible/spoken dollar amounts, including unused-card purchases. Never treat texture as the only identifier. A learner may direct another person to move cards and state the comparison.
Revision prompt: Replace “the large bundle is cheapest for any wall” with an audience- and quantity-specific statement plus “before unknown delivery”. This source is invented; no real purchasing decision follows.
Original resource rights: © NeuroForgeIO Pty Ltd 2026, SubjectNest, CC BY 4.0. Credit author, source, licence and changes. Interactive code uses Apache-2.0.