8-99中有多少4的倍數?

23..................

Multiples of 4 can be written as 4n where n is an integer

For all multiples of 4 falling within 8 - 99, we have 8 <= 4n <= 99 or 2 <= n <= 24.75

Since n is an integer, n should range from 2 to 24 in order to satisfy all the 4-multiples between 8 and 99. Therefore, the number of 4-multiples in 8-99 is 24-2+1 = 23.

99 -8 + 1 = 92 numbers
there are 23 intervals, 4 units each

8,9,10,11 - interval 1
12, 13,14,15 - interval 2
...
96, 97, 98, 99 - interval 23

so there are 23 numbers which can be divided by 4.

4x2=8
4x3=12
4x4=16
4x5=20
4x6=24
4x7=28
4x8=32
4x9=36
4x10=40
4x11=44
4x12=48
4x13=52
4x14=56
4x15=60
4x16=64
4x17=68
4x18=72
4x19=76
4x20=80
4x21=84
4x22=88
4x23=92
4x24=96