The DIG operator should work regardless of the number value, but it only works with the right-most digits 0 to 4.

Try something like this to test it;
Code:
Main:
  MeasureResult = 62928
    RX[0] = MeasureResult DIG 4
    RX[1] = MeasureResult DIG 3
    RX[2] = MeasureResult DIG 2
    RX[3] = MeasureResult DIG 1
    RX[4] = MeasureResult DIG 0
    HSEROUT ["MeasureResult = ",DEC5 MeasureResult]
    HSEROUT [" DIG's = ",DEC RX[0],DEC RX[1],DEC RX[2],DEC RX[3],DEC RX[4],13,10]
HERE:
    GOTO HERE

Returns; MeasureResult = 62928 DIG's = 62928 with PBP v2.46
What version are you using?