Solution:

6380

2*2-1 3*3-1 =>38
4*4-1 5*5-1 =>1524 and so on

Solution:

Step 1) Pour 1 liter of Water from gallon A to gallon C. Now 4 liter of Water is left in the gallon A and gallon C is full.

Step 2) Pour Water from gallon C to gallon B. Now as soon as gallon B is full , you know there is one liter of Water is in gallon C.

Solution:

Steps
1. Monica go from side A to B for approx 59 minutes
2. Lisa then move back to side A for 2 minutes to fool guard. Now guard will think she is coming to side A.
3. then she again move toward B :-)

Solution:

Of course, it is impossible. Into the second room should have gone the 2nd guest, because the 13th guest was waiting in room number 1

Solution:

Both would be the same distance from City owlna. (since they are at a same point)

Solution:

Nine (eight sons have same one sister ,so 8+1=9)

Solution:

Simply push the cork into the bottle and shake the marble out.

Solution:

4 socks

Although there are many socks in the draw, there are only three colors. So, four socks are enough to match one pair.

Solution:

Kristen Stewart is the youngest

Solution:

99+9/9 = 100