Answer :
assuming you meant 6x198 do a mental sum for 6x200 (1200) then subtract 6x2(12)to give you 1188
In this problem, we are asked to give an expression that can be used to mentally multiply 6 and 198. In order not to go through the rigorous multiplication, we can estimate 198 to 200, that is 6 *200 equal to 1200. Since there is a 2*6 excess or 12 then we subtract: 1200 -12 equal to 1188.
