Mental math

[Sj17]

When is the best age to teach mental math to children? My 7 year old is in "expected" progress in math with the school curriculum. Some of his super talented friends are very advanced in mental maths and he is influenceed by them. I am wondering is it too early for him to start mental math, before properly visualising the number? If thats normal age then How to help him in mental math?

Sounds like his 'super talented' friends may be doing kumon, which apparently doesn't help much in the long run but can make them seem pretty proficient in mental arithmetic for a while.

Yes, that's what I believe about long run. The kids dont do kumon, alot of math website like duck duck goose etc. Parents are also teaching them I think...!!