Estimation and Rounding Off Numbers
We come across many situations in our daily life such as:
(1) 15,500 people approximately attended the city’s book fair in the month of December.
(2) 8 lakh vehicles roughly pass through the city’s toll plaza every month.
(3) 72,300 tonnes of rice is shipped from the Kandla port every year.
Note: The words 'nearly', 'approximately', 'roughly' do not show the exact number of people or material. In fact, 15,500 may be 15,475 or 15,520, i.e., it may be a little less or more, but not exact.
Estimation is also a good way of checking answers. We usually round off numbers to the nearest 10's, 100's, 1000's, 10000's, etc.
Rounding off the numbers to the nearest tens:
Now, see the sequential number order.
| 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 |
61 is nearer to
So, 61 will be rounded off to 60.
68 is nearer to
So, 68 will be rounded off to 70.
Rounding off the numbers to the nearest hundreds:
| 500 | 510 | 520 | 530 | 540 | 550 | 560 | 570 | 580 | 590 | 600 |
530 is nearer to
570 is nearer to
Question: What is the rounding off number for 545? Why?