Question

If a, b, c, and d are replaced by four different digits from 1 to 9, inclusive, then what's the largest possible value for a.bc + 0.d ?

Answer 1

The place values of a,b,c and d are
1, 0.1, 0.01 and 0.1

So the largest possible values should be in order of the place values, i.e.
a,b,d,c = 9.86+0.7 = 10.56
or
a,d,b,c = 9.76+0.8 = 10.56

Answer 2

a.bc will be 9.86 and 0.d will equal 0.7

so we have 9.86 + 0.7 = 10.57 (answer).