Using Loop
To convert Decimal to binary we check if the number is divisible by 2, if yes then we take a string and append 0 to and and if not then append 1 to it and divide the number by 2 and do the same again.
finally we reverse the string and print the result
numb = 121
binary = ''
while(numb):
if(numb % 2 == 0):
binary += '0'
else:
binary += '1'
numb = numb//2
''.join(reversed(binary))
print(binary)
Using Inbuilt function
converting decimal to binary is quite easy
a = bit(121)
print(a[2:])