4175 How many four digit codes using digits can be created w

4.175 How many four -digit codes using digits can be created with repetition of digits? [Note: There are 10 digits: 0. 1.2.....9 and a Code can start with a zero] 4.176 How many four digit numbers exist with repetition of digits? [Note: There are 10 digits: 0. 1.2....? and to be a four digit number the first digit Cannot be zero.] 4.20 HOW many ways can three out at eight horses cross a finish line?

Solution

175 - No of codes = 10*10*10*10 = 10⁴(ans)

176 No of 4 digit nos = 9 * 10³ (ans) ( the first no cant be 0)

201= 8C₃ = 8*7*6*/ 6 = 56 (ans)