If the divisor is 40 what is the least three-digit dividend tag would give a remainder of 4

Let the three digit dividend be abc , 

then abc = 40*Q+4

So, abc is "40 times Q (the quotient, a number) plus 4"

we try a few values of Q for which 40Q+4 is a 3 digit number:

for Q=2

40*2+4=80+4=84

for Q=3

40*3+4=120+4=124

124