Dear student,
Let the multiplier be the 3-digit number XYZ.
We know 999 times XYZ is a number with last three digits 193:
XYZ999 = ???193
999 times XYZ is 1000 times XYZ, minus 1 times XYZ:
1000XYZXYZ = ???193
1000 times XYZ is a number that ends with 3 zeros. The 3-digit number XYZ, subtracted from a number that ends with 3 zeros, equals a number with last 3 digits 193. That gives us only one possible value for XYZ:
XYZ000XYZ = ???193
???193XYZ = XYZ000
XYZ = 807
Hence the multiplication becomes 807999806193
N.B- The multiplier is any integer with last 3 digits 807
Regards