Missing number is 6. All opposite numbers add up to 21.

缺少的数字是6，每组相对数字的和为21。 。

youdao

Although the Piraha people might not need Numbers, think of what they're missing.

虽然皮拉罕人不需要数字，但是他们也丢失了很多。

youdao

Although the Piraha people might not need Numbers, think of what they're missing.

虽然皮拉罕人不需要数字，但是他们也丢失了很多。

youdao