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 251-260 of 600 questions.
What is the sum of the first (43) natural numbers?
B. (946)
\(S_{43}=\frac{43\cdot44}{2}=946\)। सम संख्या को पहले (2) से भाग देना आसान होता है। / \(S_{43}=\frac{43\cdot44}{2}=946\). Dividing the even number by (2) first makes it easy.
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If \(1+2+3+\cdots+n=1035\), what is the value of (n)?
C. (45)
\(\frac{45\cdot46}{2}=1035\), इसलिए (n=45)। ऐसे प्रश्नों में विकल्पों को सूत्र में रखकर जांचें। / \(\frac{45\cdot46}{2}=1035\), so (n=45). In such questions, check the options in the formula.
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How much is the sum of natural numbers from (31) to (40)?
B. (355)
योग \(S_{40}-S_{30}=820-465=355\) है। सीमा से पहले तक का योग घटाना न भूलें। / The sum is \(S_{40}-S_{30}=820-465=355\). Do not forget to subtract the sum before the lower limit.
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What is the difference between the sums of the first (55) and first (45) natural numbers?
C. (505)
\(S_{55}-S_{45}=1540-1035=505\)। दोनों योग अलग-अलग निकालकर अंतर लें। / \(S_{55}-S_{45}=1540-1035=505\). Find both sums separately and then take the difference.
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If \(S_n=1225\), what will be the value of \(S_{n+2}\)?
B. (1326)
\(1225=S_{49}\), इसलिए \(S_{51}=\frac{51\cdot52}{2}=1326\)। पहले (n) पहचानें फिर नया योग निकालें। / \(1225=S_{49}\), so \(S_{51}=\frac{51\cdot52}{2}=1326\). First identify (n) and then find the new sum.
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If \(S_n-S_{n-1}=42\), what is the value of (n)?
C. (42)
\(S_n-S_{n-1}=n\) होता है, इसलिए (n=42)। दो क्रमिक योगों का अंतर अगला पद होता है। / \(S_n-S_{n-1}=n\), so (n=42). The difference of two consecutive sums is the next term.
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C. (1620)
\(S_{60}-S_{20}=1830-210=1620\)। यह (21) से (60) तक का योग है। / \(S_{60}-S_{20}=1830-210=1620\). This is the sum from (21) to (60).
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If \(S_n=666\), what will be \(S_{n+1}\)?
B. (703)
\(666=S_{36}\), इसलिए \(S_{37}=\frac{37\cdot38}{2}=703\)। अगले योग में अगला पद जुड़ता है। / \(666=S_{36}\), so \(S_{37}=\frac{37\cdot38}{2}=703\). The next sum adds the next term.
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What will be the sum of natural numbers from (41) to (50)?
B. (455)
योग \(S_{50}-S_{40}=1275-820=455\) है। बीच की श्रेणी के लिए पिछले योग को घटाएं। / The sum is \(S_{50}-S_{40}=1275-820=455\). For a middle range, subtract the previous sum.
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If \(S_n=1770\), what is the value of (n)?
B. (59)
\(\frac{59\cdot60}{2}=1770\), इसलिए (n=59)। विकल्पों को सूत्र से मिलाकर उत्तर तय करें। / \(\frac{59\cdot60}{2}=1770\), so (n=59). Decide the answer by matching options with the formula.
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