The practice engine
Practice drills
Every problem is generated from a seed and graded exactly, with the worked solution shown after each answer. The mixed drill below rotates all six skills and leans toward the ones you have missed recently; each tool page also carries a single-skill drill. Progress is stored in your browser only.
Mixed drill: all six skills
Unlimited generated problems with exact answers and worked steps. Skills you miss recently appear more often.
Timed exam mode
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Your mastery
Accuracy, streaks, and daily counts live in this browser. Clearing site data resets them.
Progress analytics
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Drill a single skill
Transposition, Prentice's rule, vertex compensation, blank size, meridian power, and vertical imbalance each pair their calculator with a dedicated drill.
Frequently asked questions
How do the practice drills work?
Each drill is generated from a seed, so problems never repeat from a fixed bank and every answer is computed exactly with a step-by-step worked solution. Type your answers and check them; misses lower a skill's mastery and make that skill appear more often.
What is exam mode?
A timed run with a configurable question count and clock across all six skills, scored at the end. Untimed drills are always available; the timer is the exam-pressure add-on.
Is my progress uploaded?
No. Mastery, streaks, and daily counts are stored in your browser only. Clearing site data resets them.