求Sn=a+aa+aaa+aaaa+…+aa…aaa(n个a)

来源：百度知道 编辑：UC知道 时间：2024/06/17 19:05:30
其中a是一个由随机数产生的1～9（包括1、9）中的一个正整数，n是一个由随机数产生的4～9（包括4、9）中的一个正整数
例如，当a=2，n=5时，Sn=2+22+222+2222+22222
使用循环结构作的...谢谢大家帮我想一想啦....

dim s As string
dim i as integer
dim m as integer
dim sn as long
dim k As long
Randomize
a=int(rnd*9)+1
n=int(rnd*6)+4
k=0
for i=1 to n
s=""
for m=1 to i
s=s & a
next m
k=s
sn=sn+k
next i
msgbox sn

Private Sub Command1_Click()
Dim i As Long, j As Long, a As Long, n As Long, Sn As Long, t As Long 'Sn、t和i必须用长整型而不能只用整型，否则有可能溢出
Randomize
a = Int(9 * Rnd + 1)
Randomize
n = Int((9 - 4 + 1) * Rnd + 4)
Sn = 0
For i = 1 To n
t = 0
For j = 1 To i
t = t + a * (10 ^ (j - 1))
Next
Sn = Sn + t
Next
Print "a =" & a
Print "n =" & n
Print "Sn=" & Sn
End Sub