RSA key pair has 3 part: modulus \(n\) , encryption key exponent \(e\), decryption key exponent \(d\). Plain text is an unsigned integer \(m\), not larger than modulus and Cipher text is also an unsigned integer \(c\).
In Encryption we have:
\[c = m^{e} \mod{n}\]
In Decryption we have:
\[m = c^{d} \mod{n}\]