Answer:
[tex]\boxed{3}[/tex]
Step-by-step explanation:
x = 1! + 2! + 3! + 4! + 5! + ... + 2020!
x = 1 + 2 + 6 + 24 + 120 + 720 + ..0 + 0 +.... + ....0
x = 33 + 120 + ...0 + ...0 + .... + ...0
x = ......3
→ So, the first unit digit of x is 3
the first unit digit is 3
n! = n × (n - 1) × (n - 2) .... × 3 × 2 × 1
