Find the missing number?

Concept: In each diamond, multiplying the number in the Top cell by the number in the Bottom cell gives a two-digit result, and this result is split so that its tens digit appears in the Left cell and its units digit appears in the Right cell: Top × Bottom = (Left × 10) + Right.

Application:

1. First diamond: Top = 7, Bottom = 6, so 7 × 6 = 42; the Left cell shows 4 and the Right cell shows 2, matching the tens and units digits of 42.

2. Second diamond: Top = 9, Bottom = 9, so 9 × 9 = 81; the Left cell shows 8 and the Right cell shows 1, matching the tens and units digits of 81.

3. Third diamond: Top = 5, Bottom = 3, so 5 × 3 = 15; the Left cell shows 1 and the Right cell shows 5, matching the tens and units digits of 15.

4. Fourth diamond: Top = 6, Bottom = 2, so 6 × 2 = 12; the Left cell already shows 1, which is the tens digit of 12, and the missing cell should hold the units digit, so the diamond's completed two-digit value is 12.

Cross-check:

1. The Left cell of the fourth diamond (1) independently matches the tens digit of 12, confirming the product 6 × 2 = 12 rather than any other candidate value, none of which can be produced by multiplying this diamond's own Top and Bottom entries.

Answer: 12