Hello, 
I don’t know if the error mentionned by Sergey82K has been fixed, but i have the same error on my DSO203. The frequency seems to be measured correctly but the measure (Hz or KHz or MHz) is not displayed correctly.
Hardware ver 2.60
Serial no 223D70DA
SYS ver 1.51
APP ver 2.52
Here are some screenshots :
10Hz -> 10.03Hz -> It seems to be correct.
100Hz -> 100.4Hz -> It seems to be correct.
1000Hz -> 1.007KC -> If KC means KHz, It seems to be correct.
10000Hz -> 10.03Hz -> It is wrong, it should be 10.03Khz or maybe 10.03KC.
100000Hz -> 104.7Hz -> It is wrong, it should be 104.7Khz or maybe 104.7KC.
500000Hz -> 546.7Hz -> It is wrong, it should be 546.7Khz or maybe 546.7KC.
1000000Hz -> 1.169KC -> It is wrong, it should be 1.169Mhz or maybe 1.169MC.
If you have a fix for this, please let me know.
Thanks,