YOU SAID:
We need to walk 10000 steps today.
INTO JAPANESE
今日は10000歩歩く必要があります。
BACK INTO ENGLISH
I need to walk 10,000 steps today.
INTO JAPANESE
今日は1万歩歩く必要があります。
BACK INTO ENGLISH
I need to walk 10,000 steps today.
Come on, you can do better than that.