A digital counter increments its count every $0.1 \mu \mathrm{~s}$. The counter is used in an instrument to measure frequency. The counter is operated for one period of the input signal to the instrument to measure its frequency. The input signal is approximately at $100$ $\mathrm{kHz}$. The maximum error in the measured frequency is $\_\_\_\_$ $\mathrm{kHz}$. (rounded off to the nearest integer)
