ℂ 2102 DOUBLE-STRUCK CAPITAL C
= the set of complex numbers
# <font> 0043 latin capital letter c
ℚ 211A DOUBLE-STRUCK CAPITAL Q
= the set of rational numbers
# <font> 0051 latin capital letter q
ℝ 211D DOUBLE-STRUCK CAPITAL R
= the set of real numbers
# <font> 0052 latin capital letter r