if a four-digit number is formed from six digits 0, 4, 5, 6, 7 and 8, how many numbers can be divisible by 5?
答案係5P3 + 4C1 X 4P2 = 108
但係我唔明條式點樣寫出嚟,求高人指點thx
也會怕有一天會pk2021-04-16 02:13:05
首先你要知道can be divisible by 5 = 尾數可以係0或者5,兩個cases,跟住搵左兩個cases既數目再加埋。