до тысячных a=2,1264 b=3,1145

a+b = 2,1264 + 3,1145 = 5,2409

a-b = 2,1264 - 3,1145 = -0,9881

a*b = 2,1264 * 3,1145 = 6,6267528

a:b = 2,1264 / 3,1145 ≈ 0,6827