YOU SAID:

I don't know how to do long division, or multiplication.

INTO JAPANESE

長い割り算や乗算をする方法がわかりません。

BACK INTO ENGLISH

I don't know how to do long divisions or multiplications.

INTO JAPANESE

長い割り算や掛け算のやり方がわからない。

BACK INTO ENGLISH

I don't know how to do long divisions or multiplications.