Brain Teasers and Puzzles

A box for your workings out:

Hint: The answer involves multiplication.

Answer: 468.

Each line is generated by multiplying two digits at a time of the previous line.

986888 = (9x8)(6x8)(8x8) = 724864 = (7x2)(4x8)(6x4) = 143224 = (1x4)(3x2)(2x4) = 468.