The answer is a 9-digit number.

To find it, get a calculator and press these keys:

12×11×10×9×8×7×6×5×4×3×2×1

then record the number you see on your calculator in the answer box

If you use a cheap calculator that only handles up to 8-digit numbers,
that will be too big a number for it to handle and you'll get an error
message.  In that case leave out 10, that is, press

12×11×9×8×7×6×5×4×3×2×1

which won't be too big and then stick a 0 on the end of the result.

Edwin