Solution:

As you see in the image, we had to move just the circle number 1, 7 and 10 and it is done.

Solution:

63.984375

Explanation:
This question is hypothetical because you cannot transact in fractions in bank account. The following is the solution:

Year Amount Interest and Deduction
Start 63.984375
Y1 End 62.968750 63.984375 * 2 - 65
Y2 End 60.937500 62.96875* 2 - 65
Y3 End 56.875000 60.9375 * 2 - 65
Y4 End 48.750000 56.875 * 2 - 65
Y5 End 32.500000 48.75 * 2 - 65
Y6 End 0.000000 32.5 * 2 - 65 = 0

Solution:

457730 * 4 = 1830920
(DOLLAR * 4 = QUARTER)

Solution:

    35997
+ 284508
========
    320505
========

Solution:

17

Explanation :
The relationship holds for below formula :
pow(x,3) - pow(x,2) - 1
=> 9*9*9 - 9*9 - 1
=> 729 - 81 - 1
=> 647

Similarly,
17*17*17 - 17*17 - 1
=> 4913 - 289 - 1
=> 4623

Solution:

26

Explanation:
14 = 1^2 + 2^2 + 3^2
21 = 4^2 + 1^2 + 2^2
29 = 4^2 + 3^2 + 2^2
26 = 3^2 + 4^2 + 1^2

Solution:

111111111

Explanation:
It's a maths magical square root series as :
Square root of number 121 is 11
Square root of number 12321 is 111
Square root of number 1234321 is 1111
Square root of number 123454321 is 11111
Square root of number 12345654321 is 111111
Square root of number 1234567654321 is 1111111
Square root of number 123456787654321 is 11111111
Square root of number 12345678987654321 is 111111111 (answer)

Solution:

19

Explanation:
The Cost of 1st Wizard is: 50 i.e Total coins spend: 50
The Cost of 2nd Wizard is: 100 i.e Total coins spend: 150
The Cost of 3rd Wizard is: 150 i.e Total coins spend: 300
The Cost of 4th Wizard is: 200 i.e Total coins spend: 500
The Cost of 5th Wizard is: 250 i.e Total coins spend: 750
The Cost of 6th Wizard is: 300 i.e Total coins spend: 1050
The Cost of 7th Wizard is: 350 i.e Total coins spend: 1400
The Cost of 8th Wizard is: 400 i.e Total coins spend: 1800
The Cost of 9th Wizard is: 450 i.e Total coins spend: 2250
The Cost of 10th Wizard is: 500 i.e Total coins spend: 2750
The Cost of 11th Wizard is: 550 i.e Total coins spend: 3300
The Cost of 12th Wizard is: 600 i.e Total coins spend: 3900
The Cost of 13th Wizard is: 650 i.e Total coins spend: 4550
The Cost of 14th Wizard is: 700 i.e Total coins spend: 5250
The Cost of 15th Wizard is: 750 i.e Total coins spend: 6000
The Cost of 16th Wizard is: 800 i.e Total coins spend: 6800
The Cost of 17th Wizard is: 850 i.e Total coins spend: 7650
The Cost of 18th Wizard is: 900 i.e Total coins spend: 8550
The Cost of 19th Wizard is: 950 i.e Total coins spend: 9500
The cost of 20th Wizard is: 1000 i.e Total coins spend: 10500 .... more than 10,000.

Solution:

142857

Explanation:
142857 * 1 = 142857
142857 * 2 = 285714
142857 * 3 = 428571
142857 * 4 = 571428
142857 * 5 = 714285
142857 * 6 = 857142

Note: Such numbers are called cyclic numbers.

Solution:

15/4 hours

Explanation:
Let us say they drive for "t" hours and initial fuel is "f"
Amount of fuel consumed by Fernando car is ft/4
Amount of fuel consumed by Sebastian car is ft/5

As per given condition,
f - ft/5 = 4(f-ft/4)
t = 15/4 hours