Multiplication by a constant can be done very efficiently. So if you know by what factor you are going to multiply, you could use one of these tricks:

multiply d0 by 29:

Code:

move.l d0, d1
lsl.l #4, d0
sub.l d1, d0
add.l d0, d0
sub.l d1, d0

multiply d0 by 625:

Code:

move.l d0, d1
lsl.l #2, d0
add.l d1, d0
lsl.l #3, d0
sub.l d1, d0
lsl.l #4, d0
add.l d1, d0

multiply d0 by 156:

Code:

move.l d0, d1
lsl.l #2, d1
add.l d1, d0
lsl.l #5, d0
sub.l d1, d0