Teacher is buying pencils for 315 students. The pencils are sold in boxes of tens. How can she use rounding to decide how many pencils to buy?How...

The problem is telling about the utility and application
of rounding.

The number of students =
315.

The number of pencils in a bos =
10.

Since each pencil box has 10 pencils, teacher has
to purchase  a number nearest 10  to 315 . There are two nearest 10's: 310 or 320 . But
with 310 pencils , it is short of 5 pencils for 315 students, if she gives one pencil to
each.

With 320 pencils, she can give one each to 315
students and retain extra 5 pencils.

So the number boxes of
pencils each containing 10 pencils to be purchased by the teacher = 320/10 =
32