There is a mystery number between 337 and 400.

the sum of all the digits is 12.
what is the mystery number?

3 answers

take your pick ...

345 , 354 , 363 , 372 , 381 , 390
let the unit digit be x and the tens digit be y
so 3 + x + y = 12
x+y = 9
and the lead digit has to be 3, so possible cases
345
354
363
372
381
390

Was there more information given?
Look at the first of the "Similar Questions" below.
the answer is 363