The sum of my digits is 12. when rounded off to the nearest hundred. i am 500. rounding to the nearest 10 makes me 530. what am I?

A number rounding to 500 must be between 450 and 549

A number rounding to 530 will be between 525 and 534 so it must be one of these numbers.

Then if you do trial and error and add all the digits you will come to 5+3+4 which = 12

The answer is therefore 534