EntityQ11563· pop 223numberthumb|Set inclusions between the [[natural numbers ]]Connectionscomplex numberEntitypositional notationEntityexponentiationEntitydecimalEntityLeonhard EulerEntityPiConceptInternational Standard Book NumberEntitynatural numberEntityinfinityEntityreal numberEntityInternational Standard Serial NumberEntityirrational numberEntityEuler's numberEntitynumeralEntityDiophantus of AlexandriaEntitynegative real numberEntityparityEntitysubsetEntityimaginary unitEntityGoldbach's conjectureEntity