How to play

Look at the green plot y = f(x) and guess the formula for f(x) in postfix. Type one character per number or operator:

• x, 1, or 2 (values)
• q for "squared" (unary)
• c for "cubed" (unary)
• s for sine
• e for exp (e to the ...)
• l for natural log
• +, -, *, / for basic operations

Or use the grid of buttons. Inputs to - and / are still taken in the usual order, so "2 x -" is two minus x.

For example, write 1 / (sin² x) as "1 x s q /", or ln(2) e^x as "2 l x e *".

Your answer will be coloured as feedback. Green: correct, right spot. Yellow: correct, wrong spot. Grey: not in answer

Remember that 1 and 2 can be used to build other, more complicated constants. Remember how syntax narrows down your options: operators tend to be near the end, and inputs near the start. Axis ticks show x = ±1 and y = ±1.

Got it