Sort coins by value. Stack them. Count by tens, by fives. Total your handful. Money is arithmetic you can hold.
Try this
67
fewest US coins = greedy: quarters, then dimes, nickels, pennies = 2×25¢ + 1×10¢ + 1×5¢ + 2×1¢ (6 coins)
The biggest-coin-first trick
To make an amount with the fewest US coins, keep taking the largest coin that still fits: quarters, then dimes, then nickels, then pennies. That 'greedy' rule happens to give the true minimum for US coins — drag the slider and count.
Your turn
What's the fewest US coins that make 41¢?
Watch out
Greedy is not always optimal for every coin system. With a hypothetical 1-, 3-, 4-cent set, making 6¢ greedily gives 4+1+1 (3 coins) but 3+3 is just 2. US coins are designed so greedy always wins.
Try it
3 quarters, 4 dimes, 7 nickels, 12 pennies
75 + 40 + 35 + 12 = $1.62.
Always count the biggest coins first. Easier on the brain — and that's how cashiers do it.