Page 46 - Math Genius C3

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\ 01-Oct-2025 Bharat Arora Proof-10 Reader’s Sign _______________________ Date __________

Example 1: Find the actual sum and the estimated sum by rounding off the numbers to
the nearest 10.

(a) 46 + 72 (b) 312 + 194
Solution:

(a) Actual Sum Estimated Sum (b) Actual Sum Estimated Sum

H t O H t O H t O H t O

1 1 1 1
4 6 rounded up 5 0 3 1 2 rounded down 3 1 0
+ 7 2 rounded down + 7 0 + 1 9 4 rounded down + 1 9 0
1 1 8 1 2 0 5 0 6 5 0 0

Example 2: Atul bought a chocolate for `149 and a packet of biscuits for `35. Estimate the
amount he spent by rounding off the numbers to the nearest 10. Is the total estimated

amount more or less than the actual amount?
Solution: Actual Sum Estimated Sum
Think Tank
H t O H t O What is easier to find, estimated

1 sum or actual sum? Which is more
1 4 9 rounded up 1 5 0 accurate?
+ 3 5 rounded up + 4 0 The estimated sum is more than
1 8 4 1 9 0 the actual sum.

practice time 2g

Find the actual sum and the estimated sum by rounding off the numbers to the nearest
10. Compare the actual and the estimated sum and fill in <, > or = in the given space.

1. 2.
t O H t O t O H t O
3 4 round off 2 2 round off
+ 6 5 round off + + 8 7 round off +

Actual Sum__________Estimated Sum Actual Sum__________Estimated Sum

3. t O H t O 4. t O H t O

4 6 round off 2 5 round off
+ 3 7 round off + + 6 9 round off +

Actual Sum__________Estimated Sum Actual Sum__________Estimated Sum

44 Mathematics-3