Bài 21) Từ style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.8pt;mso-no-proof:yes"> 10 chữ style="font-size:12.0pt; mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family: Calibri;mso-bidi-font-family:Calibri;color:black;letter-spacing:1.05pt; mso-no-proof:yes"> số style="font-size:12.0pt;mso-bidi-font-size: 11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family:Calibri;mso-bidi-font-family: Calibri;color:black;letter-spacing:1.05pt;mso-no-proof:yes"> 0, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 1, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 2, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 3, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 4, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 5, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 6, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 7, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 8, style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.95pt;mso-no-proof:yes"> 9 có style="font-size:12.0pt; mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family: Calibri;mso-bidi-font-family:Calibri;color:black;letter-spacing:1.05pt; mso-no-proof:yes"> thể style="font-size:12.0pt;mso-bidi-font-size: 11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family:Calibri;mso-bidi-font-family: Calibri;color:black;letter-spacing:1.0pt;mso-no-proof:yes"> lập style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.05pt;mso-no-proof:yes"> được style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.25pt;mso-no-proof:yes"> bao nhiêu style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.05pt;mso-no-proof:yes"> số style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.05pt;mso-no-proof:yes"> khác style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.0pt;mso-no-proof:yes"> nhau style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.05pt;mso-no-proof:yes"> sao style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:1.05pt;mso-no-proof:yes"> cho trong các style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.3pt;mso-no-proof:yes"> chữ style="font-size:12.0pt; mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family: Calibri;mso-bidi-font-family:Calibri;color:black;letter-spacing:.3pt; mso-no-proof:yes"> số style="font-size:12.0pt;mso-bidi-font-size: 11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family:Calibri;mso-bidi-font-family: Calibri;color:black;letter-spacing:.55pt;mso-no-proof:yes"> đó style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.35pt;mso-no-proof:yes"> có style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.55pt;mso-no-proof:yes"> mặt style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.6pt;mso-no-proof:yes"> số style="font-size:12.0pt; mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family: Calibri;mso-bidi-font-family:Calibri;color:black;letter-spacing:.35pt; mso-no-proof:yes"> 0 và style="font-size:12.0pt;mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri;mso-bidi-font-family:Calibri;color:black; letter-spacing:.3pt;mso-no-proof:yes"> số style="font-size:12.0pt; mso-bidi-font-size:11.0pt;mso-ascii-font-family:Calibri;mso-hansi-font-family: Calibri;mso-bidi-font-family:Calibri;color:black;letter-spacing:.55pt; mso-no-proof:yes"> 1. Tổ hợp
Bài 21) Từ 10 chữ số 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 có thể lập được bao nhiêu số khác nhau sao cho trong các chữ số đó có mặt số 0 và số 1.