double d = 1;
d = 1d;
d = 1D;
d = 1.2; //double is the default if there's no suffix
d = 1.2d; //The suffix is redundant here
d = .2;
d = 12e-12;
d = 12E-12;
d = 1_234e-1_2; //digit separators are allowed since C# 7
float f = 1;
f = 1f;
f = 1F;
f = 1.2f;
f = .2f;
f = 12e-12f;
f = 12E-12f;
f = 1_234e-1_2f;
decimal m = 1;
m = 1m;
m = 1m;
m = 1.2m;
m = .2m;
m = 12e-12m;
m = 12E-12m;
m = 1_234e-1_2m;