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getzgetzu
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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of 09 Aug 2006, 01:47
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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of first forty terms?



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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of 09 Aug 2006, 05:17
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sum = n(n+1)/2 = 40*41/2 = 820
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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of 13 Aug 2006, 11:49
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agree with AK 2 it is !
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heman
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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of 13 Aug 2006, 17:22
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getzgetzu
A sequence 1, 2, 3, 4. What is the tens' digit of the sum of first forty terms?
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is the Q 1+2+3+4...+38+39+40 ??

Arithmetic progression = 20[2+39]
= 20*41
= 820

Hence tens digit =2

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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of 13 Aug 2006, 18:01
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for n consecutive integers,
sum is n(n+1)/2
for 40 integers consecutive - 40*41/2=820

Tens digit 2
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A sequence 1, 2, 3, 4. What is the tens' digit of the sum of 15 Aug 2006, 03:58
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the ten digit is 2.

Sum of first n number is n( n+1) /2 = 40 ( 41) /2 = 820

tenth Digit is 2



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