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 261-270 of 600 questions.
Find the sum of natural numbers from (26) to (35).
B. (305)
योग \(S_{35}-S_{25}=630-325=305\) है। (26) से शुरू हो तो (25) तक का योग घटाएं। / The sum is \(S_{35}-S_{25}=630-325=305\). If it starts from (26), subtract the sum up to (25).
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What is the difference between the sums of the first (70) and first (60) natural numbers?
C. (655)
\(S_{70}-S_{60}=2485-1830=655\)। यह (61) से (70) तक का योग है। / \(S_{70}-S_{60}=2485-1830=655\). This is the sum from (61) to (70).
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If \(S_n=990\), what will be \(S_{n-2}\)?
B. (903)
\(990=S_{44}\), इसलिए \(S_{42}=\frac{42\cdot43}{2}=903\)। (n) पहचानकर दो पद पीछे जाएं। / \(990=S_{44}\), so \(S_{42}=\frac{42\cdot43}{2}=903\). Identify (n) and move two terms back.
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If \(S_n-S_{n-2}=79\), what is the value of (n)?
C. (40)
(S_n-S_{n-2}=(n-1)+n=2n-1) है। (2n-1=79) से (n=40)। / (S_n-S_{n-2}=(n-1)+n=2n-1). From (2n-1=79), (n=40).
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What is half of the sum of the first (24) natural numbers?
B. (150)
\(S_{24}=300\), इसलिए आधा (150) है। पहले पूर्ण योग निकालकर फिर भाग दें। / \(S_{24}=300\), so half is (150). First find the full sum and then divide.
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What is the value of \(1+2+3+\cdots+64\)?
C. (2080)
\(S_{64}=\frac{64\cdot65}{2}=2080\)। बड़े योग के लिए सूत्र का सीधा उपयोग करें। / \(S_{64}=\frac{64\cdot65}{2}=2080\). Use the formula directly for large sums.
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C. (53)
\(\frac{53\cdot54}{2}=1431\), इसलिए (n=53)। उत्तर को सूत्र से सत्यापित करें। / \(\frac{53\cdot54}{2}=1431\), so (n=53). Verify the answer with the formula.
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How much is the sum of natural numbers from (51) to (60)?
C. (555)
योग \(S_{60}-S_{50}=1830-1275=555\) है। यह लगातार (10) संख्याओं का योग है। / The sum is \(S_{60}-S_{50}=1830-1275=555\). This is the sum of (10) consecutive numbers.
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What is the difference between the sums of the first (80) and first (75) natural numbers?
A. (390)
\(S_{80}-S_{75}=3240-2850=390\)। यह (76) से (80) तक का योग है। / \(S_{80}-S_{75}=3240-2850=390\). This is the sum from (76) to (80).
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If \(S_n=300\), what will be \(S_{n+3}\)?
B. (378)
\(300=S_{24}\), इसलिए \(S_{27}=\frac{27\cdot28}{2}=378\)। पहले (n) पहचानें फिर (3) आगे बढ़ें। / \(300=S_{24}\), so \(S_{27}=\frac{27\cdot28}{2}=378\). Identify (n) first and then move (3) ahead.
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