Code:
    txbuf[1] = advar / 1000  
    txbuf[2] = (advar - txbuf[1] * 1000) /100  
    txbuf[3] = (advar-((txbuf[1] * 1000) + (txbuf[2] * 100)))/10  
    txbuf[4] = advar - ((txbuf[1] * 1000) + (txbuf[2] * 100)+ txbuf[3] * 10)