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Try this TOMATO problem from I.S.I. B.Stat Entrance Objective Problem based on Series and Integers.

## Series and Integers (B.Stat Objective)

The value of \(\sum ij\), where the summation is over all i and j such that \(1 \leq i \lt j \leq 10\)

- 2640
- 1320
- 3025
- none of these

**Key Concepts**

Series

Integers

Inequality

## Check the Answer

But try the problem first…

Answer: 1320

Source

Suggested Reading

B.Stat Objective Question 81

Challenges and Thrills of Pre-College Mathematics by University Press

## Try with Hints

First hint

required sum=1(2+3+4+….+10)+2(3+4+….+10)+3(4+5+….+10)+4(5+6+….+10)+5(6+7+….+10)+6(7+8+..+10)+7(8+9+10)+8(9+10)+9(10)

Second Hint

=54+104+147+180+200+204+189+152+90

Final Step

=1320

## Other useful links

- https://www.cheenta.com/rational-number-and-integer-prmo-2019-question-9/
- https://www.youtube.com/watch?v=lBPFR9xequA

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