YOU SAID:

i have to go to the shop to buy cake

INTO JAPANESE

ケーキを買うために店に行かなければならない

BACK INTO ENGLISH

I have to go to the store to buy the cake.

INTO JAPANESE

ケーキを買うために店に行かなければならない。

BACK INTO ENGLISH

I have to go to the store to buy a cake.

INTO JAPANESE

ケーキを買うために店に行かなければならない。

BACK INTO ENGLISH

I have to go to the store to buy a cake.