Page 90 - Ganit Kaushal

This is estimation by logic, because every time, whether it’s 24 or 26 litres, you are estimating it to 30 to fulfil
the purpose at hand.

In estimating something by logic, different people may have different answers for the same question, depending
upon their methods and logic.

For example: The estimation of the number of steps you take from the place you are sitting to your principal’s
office. In this case, different students may have different answers, and all of them are right in their own logic
and method.

Another example of logical estimation is the way Savita estimated the number of children in her school. As
explained in Example 2, Section 3.15, her section has 33 children, the other two sections of class 6 have 29
and 35 children. So, she estimated the number of children in her class to be about 100.
Along with her class, the school also has classes 7 to 10, and each class has three sections. She assumed a
similar number in each class and estimated the number of students in her school to be about 500.
Now, students are advised to estimate the following, based on their own logic and methods. Write the method
and logic of your estimation in your notebook. Check your estimation with your friends. Each may have a
different answer according to their logic.
(a) The number of times you blink your eyes in 5 minutes.

(b) The number of steps you take from your classroom to the school gate.
(c) The number of times you breathe in 5 minutes.
(d) The number of words in your mathematics book.
(e) The number of litres a mug, a bucket and an overhead tank can hold.
(f) The number of students using the school bus to travel to school.

Exercise 3.6

1. Estimate the following by rounding off to the nearest hundreds and by rounding off to the nearest tens.
Also compare these estimations with the actual values.
(a) 439 + 334 + 4317 (b) 108734 – 47599
2. Estimate the following products. Also compare these estimations with the actual values.

(a) 5281 × 3491 (b) 9250 × 29
3. Find the estimated values of the following:
(a) Quotient of 6443 ÷ 123 (b) Product of 1423 × 257
4. Estimate the number of hours you spend sleeping in a week, including the weekends. Then track the
exact number of hours and compare it with your estimate.
5. Estimate the capacity of a large bucket in your house in millilitres and litres.
6. Logically estimate the number of hours you spend at your school in a year. Write your logic and method
in your notebook.
7. Logically estimate the number of students in your school who travel by school bus. Write your logic
and method.
8. Estimate each of the following by rounding off to the nearest hundreds
(a) 640 + 892 (b) 16805 + 2666 (c) 2095532 – 58296 (d) 478539 – 47556

(e) 5381 × 3691 (f) 1493 × 793 (g) 8950 × 136 (h) 35394 – 31598

88 Mathematics-6