| 124 | The cycle of i | Easy | Lemma | Powers of iPeriodicity | |
| 125 | Dividing by a complex number | Easy | Lemma | Conjugate | |
| 126 | A modulus without multiplying | Easy | Lemma | ModulusMultiplicativity | |
| 269 | Adding complex numbers | Easy | Lemma | Arithmetic of ℂ | |
| 270 | Multiplying complex numbers | Easy | Lemma | Arithmetic of ℂ | |
| 271 | Squaring a complex number | Easy | Lemma | Arithmetic of ℂ | |
| 272 | A quotient | Easy | Lemma | Arithmetic of ℂ | |
| 273 | A Pythagorean modulus | Easy | Lemma | Arithmetic of ℂ | |
| 274 | One over i | Easy | Lemma | Arithmetic of ℂ | |
| 276 | A hundred powers of i | Easy | Lemma | Arithmetic of ℂ | |
| 1181 | Complex Fraction Simplification | Easy | Hall & Knight | Complex numbersRationalization | |
| 1185 | Power of Imaginary Unit | Easy | Hall & Knight | Powers of iModular arithmetic | |
| 1187 | Square Root of Complex Number | Easy | Hall & Knight | square root of complex numberimaginary numbers | |
| 1188 | Square Root of Complex Number | Easy | Hall & Knight | square root of complex numberimaginary numbers | |
| 1190 | Square Root of Pure Imaginary Number | Easy | Hall & Knight | square root of complex numberimaginary numbers | |
| 1193 | Complex division | Easy | Hall & Knight | complex numbersdivision | |
| 1194 | Complex division with radicals | Easy | Hall & Knight | complex numbersradicals | |
| 1195 | Simplifying a quotient of binomials | Easy | Hall & Knight | complex numberspowers of i | |
| 1196 | Complex fraction with squared numerator | Easy | Hall & Knight | complex numbersexpansion | |
| 275 | An equation with a conjugate | Medium | Lemma | Arithmetic of ℂ | |
| 1182 | Algebraic Complex Fraction | Medium | Hall & Knight | Complex numbersAlgebraic manipulation | |
| 1183 | Binomial Complex Fractions | Medium | Hall & Knight | Complex numbersRationalization | |
| 1184 | Cubic Difference Complex Fraction | Medium | Hall & Knight | Complex numbersAlgebraic identities | |
| 1186 | Square of Sum of Radicals | Medium | Hall & Knight | Complex numbersRadicals | |
| 1189 | Square Root of Complex Number | Medium | Hall & Knight | square root of complex numbersurds | |
| 1191 | Square Root with Parameter | Medium | Hall & Knight | square root of complex numberalgebraic parameters | |
| 1192 | Square Root with Two Parameters | Medium | Hall & Knight | square root of complex numberalgebraic parameters | |
| 1197 | Algebraic complex fraction combination | Medium | Hall & Knight | complex numbersalgebraic simplification | |
| 1222 | Evaluate polynomial at complex number | Medium | Hall & Knight | complex substitutionpolynomial evaluation | |
| 1223 | Evaluate cubic at complex number | Medium | Hall & Knight | complex substitutionpolynomial evaluation | |
| 1224 | Evaluate cubic with parameter | Medium | Hall & Knight | complex numbersalgebraic manipulation | |