6 lbs., 13 oz. at birth for anyone wondering.

7.5 trillion = 7.5x10^12

40 three-month intervals in 10 years

P = Pounds at birth

P x 2^40 = 7.5x10^40

P = 7.5x10^40 / 2^40

P ≈ 6.82 lbs.

P ≈ 6 lbs., 13 oz.