Two-digit times two-digit: units, crosswise, tens — carry left
Vertically & Crosswise — multiply any two-digit pair without long multiplication.
For 23 × 45: the units are 3×5 = 15 (write 5, carry 1); the crosswise is 2×5 + 3×4 = 22, plus the carry → 23 (write 3, carry 2); the tens are 2×4 = 8, plus the carry → 10. Read it off: 1035. You enter the method step by step — units, crosswise, tens — and each step unlocks only when the one before it is right. Five levels grow the numbers; the steps fade away as you climb until only a bare answer box is left, and a short timed boss caps each level.