Math Puzzles Questions

The given math puzzle follows a logic that,

1 + 4 = 5 => 1 x 4 + 1 = 5

2 + 5 = 12 => 2 x 5 + 2 = 12

3 + 6 = 21 => 3 x 6 + 3 = 21

Similarly,

8 + 11 = > 8 x 11 + 8 = 96.

Pages are denoted as 

1 - 9 = 09

10 - 99 = 90*2 = 180

100 = 03

Hence, total number of digits = 09 + 180 + 03 = 192.

394  is the code to unlock the key.

If you take the second statement, 7 is incorrect from the first statement and 1 is incorrect from the fourth statement. Hence 4 is correct, but not on the second place. From the third statement, 4 is not on the first place. Hence 4 is on the third place.

From the fifth statement either 6 or 9 is correct. But combining it with the third statement, 6 is incorrect. Hence along with the first statement, 9 is correct and on the second place.

From the third statement, 3 is correct and on the remaining first place.

By trial and error method,

P=0, Q=9, R=0 satisfies the values.

A - A - A = 20
B - B - B = 15
C - C - C = 25

A = -20
B = -15
C = -25

=> A + B + C = (-20)+(-15)+(-25) = -20 - 15 - 25 = -60.

5 + 5 = 10

5x 2 + 2 = 12

5 x 2 - 1 x 5 = 5

Hence, ∆ = 1.

A + B = 15 .... (1)

B x C = 84 .... (2)

C ÷ 4 = 3  .... (3)

B + D = 18 .... (4)

From (3), we get C = 12

From (2), we get B = 84/12 = 7

From (1), we get A = 15 - 7 = 8

From (4), we get D = 18 - 7 = 11

Hence, D = 11.

The logic in this puzzle is summing the result of [subtraction of upper two digits] & [addition of lower two digits] 

Hence, the result is  

(5 - 3) + (2 + 8) = 2 + 10 = 12.