Which of the following is not a natural

15.98% of 2199.9 = √? + 17.02% of 1799.97

(14.66)² + (343.84 ÷ 3.88 - 55.87) = ? + 91.23

1959.09 + 33.94% of 6250.06 – ? = √10609.02 + √144.24

29.98% of 549.99 = ? - 254.97 + 79.98% of 74.99 

(9/20 of 3998.93) - √2499.57 + (17.87% of 1199.67) = ?

20.99 × √4.09 × 30.09 = ? × √195.99 × 15.09

(8.08^3.03 + 59.59% of 839.83) ÷ 16.06 × 24.04 = ?³ + 1012.12

12.05² + 36.15 × 25.45 – 124.15 × 15.05 = ? × 8.08 – 64.32 × 15.98

(2879.79 ÷ 24.07) × (√624.77 + √120.88) - 35% of 1199.85 = ?