Is the ` one ' of the natural numbers and the ` one ' of real numbers the same number or a different number ?
Is there any difference amongst -LSB- math -RSB- 5 \ in \ mathbb N , 5 \ in \ mathbb Q ,5 \ in \ mathbb R -LSB- / math -RSB- , or -LSB- math -RSB- 5 \ in \ mathbb C -LSB- / math -RSB- ?