%d by python and addition ValueError: unsupported format character 'O' (0x4f) at index 2

i wrote a small function to do this job

x = 'INV-%05d'
m = x %(100+1)

i should have m = INV-0101

but i receive this error

ValueEr开发者_StackOverflow中文版ror: unsupported format character 'O' (0x4f) at index 2

this works without any problem, but i want to use an external variable

m = INV-%05d %(100+1)

-> m = INV-0101

because the original value should come from a saved variable

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0x4f, as reported in the error message, is the ASCII value for the capital letter O. It looks like you have made a typographical error, and put an O in when you want a zero.