Which 4-digit number -LRB- n -RRB- is equal for the last 4 digit of n ² ?
What is the value of a -LSB- math -RSB- 4 -LSB- / math -RSB- digit natural number -LSB- math -RSB- n -LSB- / math -RSB- such that -LSB- math -RSB- n ^ 2 -LSB- / math -RSB- ends with the same -LSB- math -RSB- 4 -LSB- / math -RSB- digits as -LSB- math -RSB- n -LSB- / math -RSB- ?