distributive property and rewrite rules

        1 5
        10 50
        100 500
        1000

        i v
        x l
        c d
        m

x moves down, v moves over

        17 * 42 = 
        xvii * xxxxii = 
        x*xxxx + x*ii + v*xxxx + v*ii + ii*xxxx + ii*ii
        cccc + xx + llll + vv + xxxxxxxx + iiii = 
        cccc + llll + xxxxxxxxxx + vv + iiii = 
        cccc + cc + c + x + iiii = 
        ccccccc + x + iiii =
        dccxiiii = 
        714