This is a web calculator (Not a calculator that calculates the web. It is a calculator that run on a website).

how to write a greek letter

to write a greek letter simply write a backslash and then the letter's name (put the first letter in capital for the capital version of the letter) example:
\delta -> δ,
\Delta -> Δ

how to define variables

to define variables you need to write "where" after the calculation and there you put the variable and then its value if you have more than one variable separate them by a semicolon ";"

example:
3*ω where ω = 5 -> 15
9*a+2*b where a = 10; b = 5 -> 100

you can put any letter(or symbol) you want for example:
3*∫ where ∫=3 -> 9

you can also put words for example:
rudolph + 10 where rudolph = 5 -> 15

constants that are supported:

• pi(π)
• phi(φ)
• euler's constant(e)
• tau(τ)