With 3 dices 10 can be thrown in the follwing ways
1) 631 - This can happen in 3!=6 ways
2) 622 - This can happen in 3!2!=3 ways
3) 541 - This can happen in 3!=6 ways
4) 532 - This can happen in 3!=6 ways
5) 442 - This can happen in 3!2!=3 ways
6) 433 - This can happen in 3!2!=3 ways
∴ Total number of favourable cases =6+3+6+6+3+3=27
Also, Total number of cases =63=216
∴ Required Probability =27216=18