Step-by-step explanation:

1.12!

=12×11×10 ×9×8×7×6×5×4×3×2×1

=479,001,600

2.4!5!

=(4×3×2×1)(5×4×3×2×1)

(24)(120)

=2,880

3.11!/5!3!

=11×10×9×8×7×6×5×4×3×2×1/(5×4×3×2×1)(3×2×1)

=39 916 800/(120)(6)

=55,440

Answer:

1. 12!

12(11)(10)(9)(8)(7)(6)(5)(4)(3)(2)(1)=479001600

2. 4!5!

4(3)(2)(1)=24

5(4)(3)(2)(1)=120

24•120

=2880

3.11!/5!3!

11(10)(9)(8)(7)(6)(5)(4)(3)(2)(1)/5(4)(3)(2)(1)•3(2)(1)

39916800/120•6

=55440