Rounding Numbers to the nearest ten on a number line. This is an interactive online quiz in which students will learn how to round and estimate numbers to the nearest ten. Each question in this quiz contains the picture of a number line with specific numbers to be rounded up. Number lines guide the process since the rule can easily be understood visually; it follows that the value of a number to the right of the place it has to be rounded to that is above 5 dictates that we round up and if it is below 5 it dictates that we round off. This activity is for students in 3rd, 4th, 5th and 6th grade to learn rounding numbers on a number line.