Drag r through the logistic map x' = r x (1-x) and watch the orbit, the unstable fixed point and the Lyapunov exponent move together. Positive lambda means nearby orbits separate; negative means they collapse. CHAOSLYAPUNOVBIFURCATION

Score options against weighted criteria with a transparent weighted-sum calculation, normalised weights and a ranked breakdown.

Hypotenuse, area, perimeter and both acute angles of a right triangle, from two legs or from a leg and the hypotenuse.

Greatest common divisor and lowest common multiple of two integers, with the Euclidean algorithm shown step by step and the gcd x lcm identity as a check.

Read a four-band resistor from its colours: two digits, a multiplier and a tolerance band, with the nearest E12 and E24 preferred values.

All 118 elements — tap two to see the compound they form.

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