In one of 800Score's CAT I got 31 question correct out of 37 and I scored 51 which is 99% in this part. Don't we need to get all correct all at least very near to get all correct to score 51 which looks highest score? Is it possible to get full score with 5-6 wrong question or with even more?

It's possible, depending on the difficulty level of those questions you missed. If you only miss very difficult questions, these count less against your score.

Further, the 99th percentile means you scored in the top 1% of test takers. This doesn't require that you get all questions right - just that you get more right than 99% of others taking the exam.

Veritas Help