Solution:

5625

n^1
75 * 75 = 5625 (sum of first 75 odd numbers).
50 * 50 = 2500 (sum of first 50 odd numbers).

Solution:

18

Solution:

114(37+38+39)

Solution:

126 people

125 people + Me
96/125 = 76.8

Solution:

20 paisa coins : 200
25 paisa coins : 124

Explanation:
Say he collect 20-paisa coins be A
Say he collect 25-paisa coins be B
=>number of 25-paisa coins = (324 - A).

Therefore,
0.20 X A + 0.25 (324 - A) = 71
=>20A + 25 (324 - A) = 7100
=>5A = 1000
=>A = 200.

Hence, number of 25-paisa coins = (324 - A) - 124.

Solution:

Lets take O as black, Y as yellow and O as orange.
R + Y + O = 60
As there are 4 times black balls than yellow balls, then
R = 4G
There are 6 more orange balls than yellow balls, so
B = Y + 6
Therefore,
R + Y + O = 60
4G + Y + Y + 6 = 60
6G + 6 = 60
6G = 60 – 6
6G = 54
G = 54/6 = 9
R = 4G = 4 x 9 = 36
B = Y + 6 = 9 + 6 =15
Finally there are 9 yellow balls, 36 black balls and 15 orange balls

Solution:

Only Statements 1 and 3 are true. the number is 499849.

7072 = 499849
499849 < 500000

Solution:

The digits of the requested two numbers obviously form descending sequences. Furthermore, if you have two pairs of numbers with equal sums, the pair of which the numbers have the smallest absolute difference, is the one of which the numbers have the largest product. Using this knowledge, the two numbers can easily be constructed by placing the digits one by one, starting with 9 and ending with 1:<br>9<br><br>8 -> 96<br><br>87 -> 964<br><br>875 -> 9642<br><br>8753 -> 9642<br><br>87531<br>Conclusion: the requested two numbers are 9642 and 87531 (and the product of these two numbers is 843973902).

Solution:

The number is: 12345679
12345679 * 9 = 111111111
12345679 * 18 = 222222222
12345679 * 27 = 333333333
And so on...

Solution:

There are multiple solutions to do so.
Solution1 :
Press 1
Press / (divide)
Press % (percent)
Press / (divide) .... this step may not require in all calculator.
Note: Three unique keys are '1', '/' and '%'

Solution2 :(My favorite)
Press 1
Press 0
Press 0
Press =
Note: Three unique keys are '1', '0' and '='