Jawaban:

4! + 3! – 2! + 1! + 0!

= (4 × 3 × 2 × 1) + (3 × 2 × 1) – (2 × 1) + 1 + 1

= (12 × 2 × 1) + (6 × 1) – 2 + 1 + 1

= (24 × 1) + 6 – 2 + 1 + 1

= 24 + 6 – 2 + 1 + 1

= (24 + 6) – 2 + 1 + 1

= 30 – 2 + 1 + 1

= (30 – 2) + 1 + 1

= 28 + 1 + 1

= (28 + 1) + 1

= 29 + 1

= 30