>>171 >>174 より

π^4 = 97 + 9/22
  = 100 - 3(19/22)
  = 100 - 3(20/23) + 9/(22・23)
  > 100 - 20(3/23) + (3/23)^2
  = (10 - 3/23)^2,

π^2 ≒ 10 - 3/23 = 9.869565