note that a number can be rounded up when the number lying on its right is 5-9 and will be rounded down when the number is 1-4
we'll have the numbers that could be rounded as 530 when it is rounded to the nearest tens
525 ---> 530
526 ---> 530
527 ---> 530
528 ---> 530
529 ---> 530
530--530
531 ----> 530
532 ----> 530
533 ----> 530
534 ----> 530
535 ----> 540
based on what we have above we can say that the answer is 534
