Coding and Decoding Questions

If BOULDER is coded as ZMSJBCP, then how will ELK be coded as?

In a certain code language, "OCEAN" is written as "PEHES". How is "RIVER" written in that code language?

If "+" means "minus", "x" means "divided by", "÷" means "plus" and "-" means "multiplied by", then
300 x 10 – 5 + 36 ÷ 57 = ?

In a certain code language, 'x' represents '+', '÷' represents 'x', '-' represents '÷' and '+' represents '-'. Find out the answer to the following question.

18 x 12 ÷ 5 - 10 + 10 = ?

If S = 19, SUN = 54 and CAKE = 20 , then MISTAKE = ?

In a certain code language, "TREASON" is written as "RKWWINX" and "POULTRY" is written as "CNXHYKT". How is "NUMBER" written in that code language?

If 56 x 11 = 9, 37 x 13 = 6, 42 x 12 = 3, then find the value of 87 x 77.

In a certain code language, “CUDGEL” is written as “FYGKHP”. How is “DAINTY” written in that code language?