Is it useful for children to learn abacus?

It's no use! There is a first-grade child who learned this abacus mental arithmetic and got 80 points in mathematics! The key is not the same as the thinking method of learning mathematics often, it is 5-ary! ! Children are easily confused, but they can't learn anything! ! In addition, a relative of mine learned it three or four years ago, and Zhengzhou won the first place in quick calculation, which should be very awesome. Last year, I transferred to Zhangjiagang to study, and my math was average in my class.