IMake The Sum 21

There are total 9 numbers available in each level. You need to click from the number available to make the sum equal to 21.You have 15 secs to do that. There are 21 levels to cross to become mathematics shark. You can refresh anytime you want and you will start from 1st level. Numbers are between 0-9 to make things simple. Your fastest time is recorded. Try to beat that.