import math

# Example initial key frequency

f$0=440\mathrm{.}0$ # A commonly used reference frequency $($A$4)$

# Calculate r $=2^(1/12)$

r $=2**(1/12)$

# Calculate frequencies for the next three higher keys

f$1=$ f$0*$ r$**1$

f$2=$ f$0*$ r$**2$

f$3=$ f$0*$ r$**3$

# Print the frequencies with two decimal places followed by $\text{'}$Hz$\text{'}$

print$($f$\text{'}\{$f$0$:$\mathrm{.}2$f$\}$ Hz$\text{'})$

print$($f$\text{'}\{$f$1$:$\mathrm{.}2$f$\}$ Hz$\text{'})$

print$($f$\text{'}\{$f$2$:$\mathrm{.}2$f$\}$ Hz$\text{'})$

print$($f$\text{'}\{$f$3$:$\mathrm{.}2$f$\}$ Hz$\text{'})$