Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

order of operations

Parentheses first, then powers, then multiplication and division, then addition and subtraction, left to right.

Examples

$0.5 \times 2 + 0.2 \times 3 + 1 = 1 + 0.6 + 1 = 2.6$ : both products before any adding.