| PI | A mathematical constant |
| TAU | ___ Day (celebration for those who shun pi as a mathematical constant) |
| PARTI | The art in a mathematical constant used as basis for design (5) |
| RATIO | Golden ___ (mathematical constant often encountered in biology) |
| EULER | Namesake of the mathematical constant e |
| PICNIC | Outdoor feast whose first two letters spell this mathematical constant: π |
| PIS | Mathematical constants |
| SERPENTINE | Word used to describe a cunning plan, a lake in Hyde Park, a mathematical curve, a river, an S-shaped figure in riding, a track and a wall - all sinuous, twisting or winding, "like a snake" (10) |
| OPERATOR | A telephonist or other technician; a symbol indicating a mathematical function; a trader; a mover; or, a wheeler-dealer (8) |
| ROTATION | A word for a spin of a planet, turn of a wheel or other axial turn; a cycle of alternating arable fields for crops or felling trees; a mathematical curl; or, any recurrent order (8) |
| FLEXURE | Word for a simple bend; a mathematical curve's turning point; the bending of a beam under a load; or, a Shakespearean servile bow (7) |
| CURL | A mathematical vector operator, also called a rotation; a ringlet of hair; an eddy; or, a weight-training exercise for strengthening one's biceps (4) |
| ANSWER | Solution to a mathematical problem, crossword or quiz; element of a fugue; or, an echo of a sound (6) |
| NULLSET | A mathematical term, in a nutshell gets distorted after deleting Planck's constant (7) |
| MEET | An assembly of horses, hounds and hunters prior to a chase; a swimming gala or other athletic event; or, a mathematical intersection (4) |
| RADIUS | Word, from "spoke, rod", for a measurement of distance from a centre point, whether in a mathematical or anatomical context (6) |
| LINEAR | Sequential, as a narrative without flashbacks; a mathematical relationship where doubling the cause doubles the effect; or, simply following a straight course (6) |
| REMAINDER | A hint about a mathematical term (9) |
| LOGARITHM | Moth a girl might turn into a mathematical aid (9) |
| LOG | Make a record of a mathematical term (3) |
