1) Draw up a outer grid.
2) Write the number on the side e.g (57 x 35) 50 and 7 on one side and 30 and 5 on the other.
3) 30 and 50 = 1500 then 30 and 7 = 210 then
5 an 50 = 250 after 5 and 7 = 35.
4) add them tougher like 1500 + 210 =1710
250 + 35 = 285 .
5) add 1710 + 285 = 1895 and that is your overall answer.