Practice focused topic-wise MCQs with answers and explanations for quick revision and exam preparation.
Difficulty select karke sirf is topic ke focused MCQs practice karein. Score, timer aur explanations student-friendly flow me milenge.
Showing 81-90 of 600 questions.
Choose the value of the sum of the first (21) natural numbers.
B. (231)
\(S_{21}=\frac{21\times22}{2}=231\) है। अगले सम गुणक (22) को पहले (2) से भाग दें। / \(S_{21}=\frac{21\times22}{2}=231\). Divide the next even factor (22) by (2) first.
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What is the sum of natural numbers from (1) to (35)?
C. (630)
\(S_{35}=\frac{35\times36}{2}=630\) है। अंतिम संख्या (35) को (n) मानें। / \(S_{35}=\frac{35\times36}{2}=630\). Take the last number (35) as (n).
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If \(1+2+3+\cdots+n=210\), what is (n)?
C. (20)
\(S_{20}=\frac{20\times21}{2}=210\) इसलिए (n=20)। बड़े योग में विकल्प से जांच करना सरल है। / \(S_{20}=\frac{20\times21}{2}=210\), so (n=20). For a larger sum, checking through options is simple.
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A chart has numbers from (1) to (23). What is the sum of all the numbers?
C. (276)
सभी नंबरों का योग \(S_{23}=\frac{23\times24}{2}=276\) है। लगातार (1) से शुरू होने पर \(S_n\) लगाएं। / The sum of all numbers is \(S_{23}=\frac{23\times24}{2}=276\). When numbers start consecutively from (1), use \(S_n\).
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Which is the sum of the first (28) natural numbers?
B. (406)
\(S_{28}=\frac{28\times29}{2}=406\) होता है। (28) का आधा (14) लेकर \(14\times29\) करें। / \(S_{28}=\frac{28\times29}{2}=406\). Take half of (28) as (14) and calculate \(14\times29\).
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If \(S_{29}\) is the sum of the first (29) natural numbers, what is the value of \(S_{29}\)?
C. (435)
\(S_{29}=\frac{29\times30}{2}=435\) है। विषम (n) में अगले पद को आधा करके गुणा करें। / \(S_{29}=\frac{29\times30}{2}=435\). For odd (n), halve the next term and multiply.
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Choose the correct sum of \(1+2+3+\cdots+34\).
D. (595)
\(S_{34}=\frac{34\times35}{2}=595\) है। अंतिम पद (34) देखकर सीधे सूत्र लगाएं। / \(S_{34}=\frac{34\times35}{2}=595\). See the last term (34) and apply the formula directly.
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What is the sum of the first (36) natural numbers?
A. (666)
\(S_{36}=\frac{36\times37}{2}=666\) है। (36) को (18) बनाकर \(18\times37\) करें। / \(S_{36}=\frac{36\times37}{2}=666\). Change (36) to (18) and calculate \(18\times37\).
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A teacher asks for the sum of roll numbers from (1) to (31). What is the correct answer?
B. (496)
\(S_{31}=\frac{31\times32}{2}=496\) है। क्रम (1) से शुरू हो तो अंतिम संख्या (n) होती है। / \(S_{31}=\frac{31\times32}{2}=496\). If the sequence starts from (1), the last number is (n).
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Find the sum of the first (45) natural numbers.
C. (1035)
\(S_{45}=\frac{45\times46}{2}=1035\) है। (46) को (23) बनाकर \(45\times23\) करें। / \(S_{45}=\frac{45\times46}{2}=1035\). Change (46) to (23) and calculate \(45\times23\).
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