Which of the following method has highest water use

If 1.123 × 3.211 = 3.122 + ______________, then the number in blank space is

What will come in the place of question mark (?) in the given expression?

[{(24) ² ÷ (6) ² } ÷ 8]⁴ = ? ÷ 5

52% of 36% of 810 = 72% of 18% of ? 

What will come in place of (?) in the given expression.

40% of (120 + 80) + 25% of 160 = ?

(22.5 × 24) ÷ 40 + 51.50 = ? ÷ 5.25

(12% of 1250 + 85% of 400) x 10 = ?²

(96% of 1100) + 92 × 4 = ? + 46 × 16

Simplify the following expression:

    (400 +175) ² - (400 – 175) ² / (400 × 175)