Coin & Stamp Problems
📋 What it is
Coin problems track TWO things at once — the NUMBER of coins and their total VALUE — using two equations.
🗣️ Coach says
A coin problem has two facts: how MANY coins, and how much they’re WORTH. “7 coins worth 55¢, dimes and nickels.” Track both: number (d + n = 7) and value (10d + 5n = 55). Two facts, two equations.
🧠 Memory hook
Coins carry TWO facts: how many, and how much. Write an equation for each.
😂 Giggle
Why did order of operations bring a to-do list?
Because it always does things in the right order!
😲 Whoa!
This “two things at once” idea (a system of equations) is exactly how GPS finds your location — it solves several distance equations at once to pin the one point that fits all of them.
✅ Quick check: 7 coins, all dimes and nickels, worth 55¢. What two facts do you track?
Say your answer out loud first — then reveal.
✏️ Check your work Substitute your two counts back into BOTH equations — do they hit the coin COUNT and the total VALUE? Both must hold, not just one.
The COUNT (dimes + nickels = 7) and the VALUE (10×dimes + 5×nickels = 55) — two equations.
Coin problems need both a count equation and a value equation.
🧪 Try it! (2 minutes)
Grab a handful of coins. Count how many (fact 1) and their total value (fact 2). See the two facts?
🔎 How did you work this?