Estimation involves approximating a quantity to an accuracy required.
4117 may be approximately to 4100 or to 4000 i.e. to the nearest hundred or to the nearest thousand depending on our need.
When we come across headlines like ‘100 people win prizes worth rupees 10000’, or ’40 million people to watch India Pakistan match’ etc. do you think that these are the exact figures? No, these are the ‘approximate’ figures. These approximate figures are known as Estimation.
When do we estimate? We estimate when we don’t have an exact figure but have an idea about it and hence help in planning things.
Estimating to the nearest tens by rounding off.
When we host a small party, we say that there are around 50-60 guests. Obviously, we did not calculate each and every person, then how did we come up with the 50 and 60 figure? We rounded the figure approximately to its nearest ten! How do we round the figure to the nearest ten? When we come across 1,2,3,4 in unit digits, then round it off to the lowest ten, and when digits like 5,6,7,8,9 are in the unit digits then the rounding off will take place in highest ten.
1. 33 people attended the workshop – around 30 people attended the workshop.
2. 87 people died in a train accident – around 90 people died in a train accident.
3. 09 rupees off on a packet of cookies – around rupees 10 off on a packet of cookies Estimating to the nearest hundreds
Similarly, in rounding off to the nearest hundreds, we will consider 10, 20, 30, 40 to the lowest hundred and 50, 60, 70, 80, 90 to the highest hundred. Example :
1. 443 foreigners visit India – around 400 visitors visit India
2. 150 people killed in a stampede, while on a pilgrimage – around 200 people killed in a stampede while they were on a pilgrimage.
3. Around 98 furniture items were sold in a day – around 100 pieces of furniture were sold.
Estimating to the nearest Thousand
When it comes to thousand, we consider 100, 200, 300, 400 to the nearest lowest thousand and 500 on wards to the nearest highest thousand.
1. 4432 packets of food were donated to villagers.
So estimated packets of food were donated to villagers were around 4000
2. Gifts worth 7900 will be free . Estimated gifts around 8000 will be free.
Can you round off the following numbers to their nearest tens, hundreds and thousands respectively?