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

(c) 3256 + 4098 (d) 5981 + 3527
th H t O th H t O th H t O th H t O

+ + + +

Critical Thinking
maths fun Social Emotional Learning
Add the numbers and find the answers in the clue box. Then, write the letters to
decode the message.
(a) 2875 + 10 = ____ (b) 4438 + 10 = ____ Clue Box

(c) 7547 + 100 = ____ (d) 6399 + 10 = ____ T 9913 7647 A
(e) 8930 + 100 = ____ (f) 8913 + 1000 = ____ 6409 E 6474 V
(g) 9398 + 100 = ____ (h) 7843 + 1000 = ____ 2885 M H 8843

(i) 4538 + 1000 = ____ (j) 6464 + 10 = ____ L 5538 9498 S
Secret message: O 4448 9030 I

(e) (i) (b) (j) (d) (a) (c) (f) (h) (g)
estimAting the sum

Siya: Did you watch the Hockey World Cup match yesterday. It was so exciting.
Rahul: Yes, I did! Do you know there were 6052 men, 2456 women and 1201 children
who went to watch the match?

Siya: Wow! It means the total number of tickets sold was around 10,000.
Rahul: Yes.

Let us see how Siya calculated the total sum around 10,000.
Estimating a sum is a rough calculation. It involves rounding the numbers before adding
them for a rough total.
For example, to find the estimated sum of 18 and 14, let us use the following steps:

Step 1: In 18, the ones digit is 8, which is greater than 5 (8 > 5).
So, 18 is rounded up to 20.
Step 2: In 14, the ones digit is 4, which is less than t O

5 (4 < 5). t O
So, 14 is rounded down to 10. 1 round up
1
2
Step 3: Now, add 20 and 10. + 1 8 round down + 1 0
4
0
Thus, the estimated sum of 18 and 14 is 30, 3 2 3 0
while the actual sum is 32. Actual Sum Estimated Sum

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