Math Puzzles Questions

Pages are denoted as 

1 - 9 = 09

10 - 99 = 90*2 = 180

100 = 03

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

3 + 5 + 6  = 151872

3x5, 3x6, Rev of (3x5 + 3x6 - 6) 

5 + 5 + 6  = 253094

5x5, 5x6, Rev of (5x5 + 5x6 - 6)

Similarly,

9x4 = 36

9x7 = 63

So 36 + 63 = 99

From 99 - 7 =  92

Reverse of 92=29

Hence, 9 + 4 + 7 =  366329.

Let the missing numbers be x, y, a and b

x + y = 8 ---- (1)
a - b = 6 ---- (2)
x + a = 13 --- (3)
y + b = 8 ---- (4)

2x + a + y = 21 --- From (1 & 3)
a + y = 14 ----  From (2 & 4)

Substitute (2 & 4) in (1 & 3)

2x + 14 = 21
2x = 7
x = 3.5

From (1) ---> 3.5 + y = 8
=> y = 8 - 3.5 = 4.5

a + y = 14 => a = 14 - y = 14 - 4.5 => a = 9.5
From (4) ---- y + b = 8 => b = 8 - y = 8 - 4.5 = 3.5

Hence,
x = 3.5
y = 4.5
a = 9.5
b = 3.5