456813
1 + 2 + 456789 = 456,792.However, you may have meant:1+2+3+4+5+6+7+8+9 which = 45
The Answer to this problem is 511112.
1 + 54 + 23 + 23 + 43 = 144
(7+89)=96/4=24-6=18+5=23
456789 * 1234567890 = 5.63937032 × 1014
456789
34.4071
If that is the only criteria then the lowest number is 456789, what you allready have.
23
1 + 2 + 1000 + 300 + 23 + 12 = 1338
1 + 1 + 22 = 24
1-14+23=10