A. Each sum has an alphabet. Multiply and write the alphabet with the matching number below. The letters tell you what Manu's birthday gift is.
82 x 41 (C)
546 x 27 (R)
826 x 35 (S)
608 x 49 (A)
Manu's Birthday gift: 3362 29792 14742 28910
B. Kritika solved the expression 5 + 2 x 3 - 1 as shown. Is her method correct? If her method is not correct, then solve it correctly.
Kritika's Method:
5 + 2 x 3 - 1
= 7 x 3 - 1
= 21 - 1 = 20
Correct Method:
5 + 2 x 3 - 1
= 5 + 6 - 1
= 11 - 1 = 10
C. Shalini solved the expression 10 ÷ 2 + (6 - 3) as shown. Is her method correct? If her method is not correct, then solve it correctly.
Shalini's Method:
10 ÷ 2 + (6 - 3)
= 5 + (6 - 3)
= 5 + 3 = 8
Correct Method:
10 ÷ 2 + (6 - 3)
= 10 ÷ 2 + 6 - 3
= 5 + 6 - 3
= 11 - 3 = 8
D. Estimate the answer in each of the following:
1. 78322 + 2697
2. 2136 + 2753
3. 86487 - 3549
4. 5365 - 3256
5. 1147 x 23
6. 5368 ÷ 35
Answer (2)
A. Let's start by solving the expressions to match the numbers with their alphabet to determine Manu's birthday gift:
82 × 41 = 3362 , which matches C.
546 × 27 = 14742 , which matches R.
826 × 35 = 28910 , which matches A.
608 × 49 = 29792 , which matches S.
Putting the letters together from the order matched numbers, Manu's birthday gift spells CARAS .
B. Kritika's method of solving the expression 5 + 2 × 3 − 1 is incorrect because she did not follow the order of operations correctly. The order of operations (PEMDAS/BODMAS) states that you perform multiplication before addition and subtraction. Let's solve it correctly:
Perform the multiplication first: 2 × 3 = 6 .
Substitute back into the expression: 5 + 6 − 1 .
Perform the addition: 5 + 6 = 11 .
Perform the subtraction: 11 − 1 = 10 .
Thus, the correct answer is 10 .
C. Shalini's method for solving 10 ÷ 2 + ( 6 − 3 ) is correct. She correctly handled the operations inside the parentheses first, then division and finished with addition:
Evaluate the parenthesis: 6 − 3 = 3 .
Perform the division: 10 ÷ 2 = 5 .
Finally, add: 5 + 3 = 8 .
So, the correct result is 8 .
D. Estimating the answers:
78322 + 2697 : Round to the nearest thousand: 78000 + 3000 = 81000 .
2136 + 2753 : Round to the nearest hundred: 2100 + 2800 = 4900 .
86487 - 3549 : Round to the nearest thousand: 86000 − 4000 = 82000 .
5365 - 3256 : Round to the nearest hundred: 5400 − 3300 = 2100 .
1147 x 23 : Round to the nearest ten for both: 1150 × 20 = 23000 .
5368 ÷ 35 : Round to the most convenient number: 5400 ÷ 30 ≈ 180 .
Thus, these estimations provide quick approximations to the arithmetic operations.
Manu's birthday gift spells CRAS based on the calculated products. Kritika's solution is incorrect, and the correct answer for her expression is 10 . Shalini's solution is correct, yielding the answer 8 , and the estimations for the arithmetic operations are provided for quick approximations.
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