We "round off" numbers in order to give a simpler look so that our brains can easily visual the number. The same rule is used "around the world". If the 1's digit is 1 or 2 or 3 or 4, then that number is dropped. This is called "rounding down". If the 1's digit is 5 or 6 or 7 or 8 or 9 the 10's digit is moved up by 1 and the 1's digit is changed to a zero.. This called 'rounding up'. You may want to use a Hundreds Chart to visualize the problem.
Round 84 Since the 1's digit is less than 5, it is dropped. Answer: 80
Round 28 Since the 1's digit is 5 or larger, the number is 'rounded up'. Answer: 30
Follow the rule to round each number to the nearest 10. Strive for accuracy and then strive to increase your speed. Good luck and enjoy the challenge!