Level 62 • 50/50 questions • 40 seconds per question.
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What is the sum of the first (10) natural numbers?
C. (55)
सूत्र (S_n=\frac{n(n+1)}{2}) से \(S_{10}=\frac{10\cdot11}{2}=55\)। परीक्षा में (n) की जगह सही संख्या रखें। / Using (S_n=\frac{n(n+1)}{2}), \(S_{10}=\frac{10\cdot11}{2}=55\). In exams, put the correct value of (n).
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Find the sum of the first (20) natural numbers.
B. (210)
\(S_{20}=\frac{20\cdot21}{2}=210\)। पहले (20) को (2) से काटना गणना आसान करता है। / \(S_{20}=\frac{20\cdot21}{2}=210\). Cancelling (20) by (2) first makes calculation easy.
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If (S_n=\frac{n(n+1)}{2}), what is \(S_{15}\)?
D. (120)
\(S_{15}=\frac{15\cdot16}{2}=120\)। गुणा करने से पहले (16) को (2) से भाग दें। / \(S_{15}=\frac{15\cdot16}{2}=120\). Divide (16) by (2) before multiplying.
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What is the value of \(1+2+3+\cdots+25\)?
A. (325)
पहले (25) प्राकृतिक संख्याओं का योग \(\frac{25\cdot26}{2}=325\) है। लंबे जोड़ में सूत्र समय बचाता है। / The sum of the first (25) natural numbers is \(\frac{25\cdot26}{2}=325\). The formula saves time in long addition.
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Which is the sum of the first (30) natural numbers?
D. (465)
\(S_{30}=\frac{30\cdot31}{2}=465\)। (30) को पहले (2) से भाग देने पर \(15\cdot31\) मिलता है। / \(S_{30}=\frac{30\cdot31}{2}=465\). Dividing (30) by (2) first gives \(15\cdot31\).
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How much is the sum of the first (12) natural numbers?
B. (78)
\(S_{12}=\frac{12\cdot13}{2}=78\)। सूत्र में (n=12) सीधे रखें। / \(S_{12}=\frac{12\cdot13}{2}=78\). Put (n=12) directly in the formula.
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Which is the correct formula for the sum of the first (n) natural numbers?
C. (\frac{n(n+1)}{2})
पहले (n) प्राकृतिक संख्याओं का योग (\frac{n(n+1)}{2}) होता है। सूत्र याद रखना इस अध्याय की मुख्य कुंजी है। / The sum of the first (n) natural numbers is (\frac{n(n+1)}{2}). Remembering this formula is the main key for this chapter.
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What is the sum of \(1+2+3+\cdots+50\)?
B. (1275)
\(S_{50}=\frac{50\cdot51}{2}=1275\)। पहले (50) को आधा करें फिर (51) से गुणा करें। / \(S_{50}=\frac{50\cdot51}{2}=1275\). Halve (50) first and then multiply by (51).
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Find the sum of the first (5) natural numbers.
C. (15)
(1+2+3+4+5=15)। छोटे (n) के लिए सीधे जोड़कर भी जांच सकते हैं। / (1+2+3+4+5=15). For small (n), you can also check by direct addition.
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What will be the sum of the first (8) natural numbers?
A. (36)
\(S_8=\frac{8\cdot9}{2}=36\)। (8) को (2) से भाग देकर \(4\cdot9\) करें। / \(S_8=\frac{8\cdot9}{2}=36\). Divide (8) by (2) and calculate \(4\cdot9\).
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Which is the sum of the first (18) natural numbers?
B. (171)
\(S_{18}=\frac{18\cdot19}{2}=171\)। आधा करके \(9\cdot19\) लिखना आसान है। / \(S_{18}=\frac{18\cdot19}{2}=171\). It is easy to write it as \(9\cdot19\).
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If the sum of the first (n) natural numbers is (120), what is (n)?
C. (15)
\(\frac{15\cdot16}{2}=120\), इसलिए (n=15)। ऐसे प्रश्नों में विकल्पों को सूत्र में रखकर जांचें। / \(\frac{15\cdot16}{2}=120\), so (n=15). In such questions, test the options in the formula.
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How much is the sum of the first (40) natural numbers?
C. (820)
\(S_{40}=\frac{40\cdot41}{2}=820\)। (40) का आधा (20) लेकर \(20\cdot41\) करें। / \(S_{40}=\frac{40\cdot41}{2}=820\). Take half of (40) as (20) and calculate \(20\cdot41\).
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What will be the value of \(1+2+3+\cdots+100\)?
B. (5050)
\(S_{100}=\frac{100\cdot101}{2}=5050\)। बड़े योग में सूत्र सीधे उपयोग करें। / \(S_{100}=\frac{100\cdot101}{2}=5050\). Use the formula directly for large sums.
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What is the sum of the first (7) natural numbers?
D. (28)
\(S_7=\frac{7\cdot8}{2}=28\)। विषम (n) में अगले सम संख्या को पहले (2) से भाग दें। / \(S_7=\frac{7\cdot8}{2}=28\). For odd (n), divide the next even number by (2) first.
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Find the sum of the first (9) natural numbers.
A. (45)
\(S_9=\frac{9\cdot10}{2}=45\)। (10) को (2) से भाग देकर \(9\cdot5\) करें। / \(S_9=\frac{9\cdot10}{2}=45\). Divide (10) by (2) and calculate \(9\cdot5\).
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If (S_n=\frac{n(n+1)}{2}), what is \(S_6\)?
B. (21)
\(S_6=\frac{6\cdot7}{2}=21\)। सूत्र में (n=6) सही ढंग से रखें। / \(S_6=\frac{6\cdot7}{2}=21\). Put (n=6) correctly in the formula.
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How much will be the sum of the first (14) natural numbers?
C. (105)
\(S_{14}=\frac{14\cdot15}{2}=105\)। पहले (14) को (2) से भाग देकर \(7\cdot15\) करें। / \(S_{14}=\frac{14\cdot15}{2}=105\). Divide (14) by (2) first and calculate \(7\cdot15\).
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What is the sum of the first (11) natural numbers?
B. (66)
\(S_{11}=\frac{11\cdot12}{2}=66\)। (12) का आधा (6) लेकर \(11\cdot6\) करें। / \(S_{11}=\frac{11\cdot12}{2}=66\). Take half of (12) as (6) and calculate \(11\cdot6\).
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If the sum of the first (n) natural numbers is (55), what will (n) be?
C. (10)
\(\frac{10\cdot11}{2}=55\), इसलिए (n=10)। विकल्पों को जल्दी जांचना आसान तरीका है। / \(\frac{10\cdot11}{2}=55\), so (n=10). Testing options quickly is an easy method.
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Which is the sum of the first (16) natural numbers?
D. (136)
\(S_{16}=\frac{16\cdot17}{2}=136\)। (16) को आधा करके \(8\cdot17\) करें। / \(S_{16}=\frac{16\cdot17}{2}=136\). Halve (16) and calculate \(8\cdot17\).
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Which is correctly written for the sum \(1+2+3+\cdots+n\)?
B. (\frac{n(n+1)}{2})
(1+2+3+\cdots+n=\frac{n(n+1)}{2}) होता है। यह मूल सूत्र हर प्रश्न में काम आता है। / (1+2+3+\cdots+n=\frac{n(n+1)}{2}). This basic formula is useful in every question.
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Find the sum of the first (13) natural numbers.
C. (91)
\(S_{13}=\frac{13\cdot14}{2}=91\)। (14) का आधा (7) लेकर \(13\cdot7\) करें। / \(S_{13}=\frac{13\cdot14}{2}=91\). Take half of (14) as (7) and calculate \(13\cdot7\).
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How much is the sum of the first (4) natural numbers?
C. (10)
(1+2+3+4=10)। छोटे योग में सीधे जोड़कर उत्तर जांच सकते हैं। / (1+2+3+4=10). In small sums, you can check the answer by direct addition.
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What will be the sum of the first (22) natural numbers?
A. (253)
\(S_{22}=\frac{22\cdot23}{2}=253\)। (22) का आधा (11) लेकर \(11\cdot23\) करें। / \(S_{22}=\frac{22\cdot23}{2}=253\). Take half of (22) as (11) and calculate \(11\cdot23\).
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If \(S_n=465\), what is the value of (n)?
C. (30)
\(\frac{30\cdot31}{2}=465\), इसलिए (n=30)। विकल्पों में से सूत्र से मिलान करें। / \(\frac{30\cdot31}{2}=465\), so (n=30). Match the options with the formula.
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How much is the sum of the first (24) natural numbers?
C. (300)
\(S_{24}=\frac{24\cdot25}{2}=300\)। पहले (24) को आधा करके \(12\cdot25\) करें। / \(S_{24}=\frac{24\cdot25}{2}=300\). First halve (24) and calculate \(12\cdot25\).
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What is the sum of the first (3) natural numbers?
C. (6)
(1+2+3=6)। शुरुआती पदों में सीधे जोड़ना सबसे सरल है। / (1+2+3=6). For the first few terms, direct addition is simplest.
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Find the sum of the first (60) natural numbers.
A. (1830)
\(S_{60}=\frac{60\cdot61}{2}=1830\)। बड़े (n) में सूत्र सीधे उपयोग करें। / \(S_{60}=\frac{60\cdot61}{2}=1830\). Use the formula directly for large (n).
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If the sum of the first (n) natural numbers is (210), what is (n)?
C. (20)
\(\frac{20\cdot21}{2}=210\), इसलिए (n=20)। सही (n) के लिए विकल्पों को सूत्र में रखें। / \(\frac{20\cdot21}{2}=210\), so (n=20). Put the options in the formula to find the correct (n).
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What is the sum of the first (17) natural numbers?
C. (153)
\(S_{17}=\frac{17\cdot18}{2}=153\)। (18) को (2) से भाग देकर \(17\cdot9\) करें। / \(S_{17}=\frac{17\cdot18}{2}=153\). Divide (18) by (2) and calculate \(17\cdot9\).
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What is the value of \(1+2+3+\cdots+19\)?
B. (190)
\(S_{19}=\frac{19\cdot20}{2}=190\)। पहले (20) का आधा (10) करें। / \(S_{19}=\frac{19\cdot20}{2}=190\). First halve (20) to get (10).
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Which is the sum of the first (2) natural numbers?
C. (3)
(1+2=3)। प्राकृतिक संख्याएं (1) से शुरू होती हैं। / (1+2=3). Natural numbers start from (1).
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What will be the sum of the first (26) natural numbers?
C. (351)
\(S_{26}=\frac{26\cdot27}{2}=351\)। (26) को (2) से भाग देकर \(13\cdot27\) करें। / \(S_{26}=\frac{26\cdot27}{2}=351\). Divide (26) by (2) and calculate \(13\cdot27\).
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If \(S_n=78\), what will be the value of (n)?
C. (12)
\(\frac{12\cdot13}{2}=78\), इसलिए (n=12)। उत्तर को सूत्र से जांचना जरूरी है। / \(\frac{12\cdot13}{2}=78\), so (n=12). It is important to verify the answer with the formula.
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How much is the sum of the first (35) natural numbers?
C. (630)
\(S_{35}=\frac{35\cdot36}{2}=630\)। (36) को आधा कर \(18\cdot35\) करें। / \(S_{35}=\frac{35\cdot36}{2}=630\). Halve (36) and calculate \(18\cdot35\).
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A student added all natural numbers from (1) to (10). What sum will he get?
A. (55)
(1) से (10) तक का योग \(S_{10}=55\) है। ऐसी स्थिति में पहले और अंतिम संख्या से (n) पहचानें। / The sum from (1) to (10) is \(S_{10}=55\). In such cases, identify (n) from the last number.
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What is the sum of the first (45) natural numbers?
B. (1035)
\(S_{45}=\frac{45\cdot46}{2}=1035\)। (46) का आधा (23) लेकर \(45\cdot23\) करें। / \(S_{45}=\frac{45\cdot46}{2}=1035\). Take half of (46) as (23) and calculate \(45\cdot23\).
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If \(S_n=325\), what will (n) be?
C. (25)
\(\frac{25\cdot26}{2}=325\), इसलिए (n=25)। विकल्पों को सूत्र से जांचें। / \(\frac{25\cdot26}{2}=325\), so (n=25). Check the options using the formula.
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How much will be the sum of the first (28) natural numbers?
A. (406)
\(S_{28}=\frac{28\cdot29}{2}=406\)। (28) का आधा (14) लेकर \(14\cdot29\) करें। / \(S_{28}=\frac{28\cdot29}{2}=406\). Take half of (28) as (14) and calculate \(14\cdot29\).
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Find the sum of the first (32) natural numbers.
C. (528)
\(S_{32}=\frac{32\cdot33}{2}=528\)। (32) का आधा (16) लेकर \(16\cdot33\) करें। / \(S_{32}=\frac{32\cdot33}{2}=528\). Take half of (32) as (16) and calculate \(16\cdot33\).
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What is the sum of the first (1) natural number?
B. (1)
पहली प्राकृतिक संख्या (1) है, इसलिए योग (1) है। प्राकृतिक संख्याएं (1) से शुरू होती हैं। / The first natural number is (1), so the sum is (1). Natural numbers start from (1).
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What is the sum of \(1+2+3+\cdots+75\)?
C. (2850)
\(S_{75}=\frac{75\cdot76}{2}=2850\)। (76) का आधा (38) लेकर \(75\cdot38\) करें। / \(S_{75}=\frac{75\cdot76}{2}=2850\). Take half of (76) as (38) and calculate \(75\cdot38\).
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If the sum of the first (n) natural numbers is (36), what is (n)?
C. (8)
\(\frac{8\cdot9}{2}=36\), इसलिए (n=8)। विकल्प को सूत्र में रखकर जल्दी जांचें। / \(\frac{8\cdot9}{2}=36\), so (n=8). Quickly check the option in the formula.
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Which is the sum of the first (23) natural numbers?
B. (276)
\(S_{23}=\frac{23\cdot24}{2}=276\)। (24) का आधा (12) लेकर \(23\cdot12\) करें। / \(S_{23}=\frac{23\cdot24}{2}=276\). Take half of (24) as (12) and calculate \(23\cdot12\).
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What is the sum of the first (27) natural numbers?
B. (378)
\(S_{27}=\frac{27\cdot28}{2}=378\)। (28) का आधा (14) लेकर \(27\cdot14\) करें। / \(S_{27}=\frac{27\cdot28}{2}=378\). Take half of (28) as (14) and calculate \(27\cdot14\).
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A teacher asked to add numbers from (1) to (15). What is the correct sum?
C. (120)
(1) से (15) तक का योग \(S_{15}=120\) है। अंतिम संख्या ही (n) होती है। / The sum from (1) to (15) is \(S_{15}=120\). The last number is (n).
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How much is the sum of the first (55) natural numbers?
A. (1540)
\(S_{55}=\frac{55\cdot56}{2}=1540\)। (56) का आधा (28) लेकर \(55\cdot28\) करें। / \(S_{55}=\frac{55\cdot56}{2}=1540\). Take half of (56) as (28) and calculate \(55\cdot28\).
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If \(S_n=91\), what is the correct value of (n)?
C. (13)
\(\frac{13\cdot14}{2}=91\), इसलिए (n=13)। उत्तर को सूत्र से अवश्य सत्यापित करें। / \(\frac{13\cdot14}{2}=91\), so (n=13). Always verify the answer with the formula.
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What will be the sum of the first (36) natural numbers?
C. (666)
\(S_{36}=\frac{36\cdot37}{2}=666\)। (36) को आधा कर \(18\cdot37\) करें। / \(S_{36}=\frac{36\cdot37}{2}=666\). Halve (36) and calculate \(18\cdot37\).
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