Coding and Decoding Questions

If signs - and x, and numbers 3 and 15 are interchanged, what is the value of 3+12/6-4x15 is

If the mathematical operators, 'x' means '+', '/' means 'x', '+' means '-', and '-' means '/', then 22 + 36 - 12 x 6 / 4 = ?

Replace # sign with the mathematical operators '+', '/','-'or'=' to get a balanced equation out of 186 # 31 # 36 # 30.

If "A" means "subtraction", "B" means "division", "C" means "addition" and "D" means "multiplication", then

294 B 7 A 40 C 33 D 11 = ?

If 12@18 = -3, 18@6 = 6 and 16@8 = 4, then find the value of 6@10 = ?

If @ means +, # means -, $ means x and * means /, then what is the value of 16 @ 4 $ 5 # 72 * 8 = 

If

4x9=25
7x4=53

then

9x4=?

If 18$6 = 6, 8$2 = 3 and 8$4 = 2, then find the value of 18$12 = ?