4. Because we calculate from 65000 to 69000. So that it must has 1 choice. 6 5 0 0 0 1 At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat.
5. Because we calculate from 65000 to 69000. So that it must has 1 choice. We have 4 number greater than 5, except 6 (1 st number).So that it must be 5-1=4 6 5 0 0 0 1 4 At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat.
6. Because we calculate from 65000 to 69000. So that it must has 1 choice. We have 4 number greater than 5, except 6 (1 st number).So that it must be 5-1=4 6 5 0 0 0 1 4 8 We have 8 numbers to chose (except 2 letters before) At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat.
7. Because we calculate from 65000 to 69000. So that it must has 1 choice. We have 4 number greater than 5, except 6 (1 st number).So that it must be 5-1=4 6 5 0 0 0 1 4 8 We have 8 numbers to chose (except 2 letters before) 7 We have 7 numbers to chose (except 3 letters before) At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat.
8. Because we calculate from 65000 to 69000. So that it must has 1 choice. We have 4 number greater than 5, except 6 (1 st number).So that it must be 5-1=4 6 5 0 0 0 1 4 8 We have 8 numbers to chose (except 2 letters before) 7 We have 7 numbers to chose (except 3 letters before) 6 At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat. We have 7 numbers to chose (except 3 letters before)
9. Because we calculate from 65000 to 69000. So that it must has 1 choice. We have 4 number greater than 5, except 6 (1 st number).So that it must be 5-1=4 6 5 0 0 0 1 4 8 We have 8 numbers to chose (except 2 letters before) 7 We have 7 numbers to chose (except 3 letters before) 6 x x x x Multiply it, we will have the total of number greater than 65000 and smaller than 69999 At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat. We have 7 numbers to chose (except 3 letters before)
10. Because we calculate from 65000 to 69000. So that it must has 1 choice. We have 4 number greater than 5, except 6 (1 st number).So that it must be 5-1=4 6 5 0 0 0 1 4 8 We have 8 numbers to chose (except 2 letters before) 7 We have 7 numbers to chose (except 3 letters before) 6 x x x x Multiply it, we will have the total of number greater than 65000 and smaller than 69999 At first, we need to know how many number from 65000 to 65999 and the numbers cannot be repeat. 1 x 4 x 8 x 7 x 6 =1344 numbers We have 7 numbers to chose (except 3 letters before)
12. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat.
13. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat. 9 We have 9 numbers to chose (except 1 letters before)
14. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat. 9 We have 9 numbers to chose (except 1 letters before) 8 We have 8 numbers to chose (except 2 letters before)
15. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat. 9 We have 9 numbers to chose (except 1 letters before) 8 We have 8 numbers to chose (except 2 letters before) 7 We have7 numbers to chose (except 3 letters before)
16. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat. 9 We have 9 numbers to chose (except 1 letters before) 8 We have 8 numbers to chose (except 2 letters before) 7 We have7 numbers to chose (except 3 letters before) 6 We have 6 numbers to chose (except 4 letters before)
17. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat. 9 We have 9 numbers to chose (except 1 letters before) 8 We have 8 numbers to chose (except 2 letters before) 7 We have7 numbers to chose (except 3 letters before) 6 We have 6 numbers to chose (except 4 letters before) x x x x
18. 7,8,9 at 1 st position can make the numbers greater than 7000 (the numbers after cannot be repeated => exclude 70000) 0 0 3 0 0 7 Then, we need to know how many number greater than 65999, from 70000 to 99999 and the numbers cannot be repeat. 9 We have 9 numbers to chose (except 1 letters before) 8 We have 8 numbers to chose (except 2 letters before) 7 We have7 numbers to chose (except 3 letters before) 6 We have 6 numbers to chose (except 4 letters before) x x x x Multiply it, we will have the total of number greater than 65999 and smaller than 99999 3 x 9 x 8 x 7 x 6=9075 numbers
19. And now, we add it together to get the 5 digit number greater than 65000. 1344+9072=10416 numbers
20. To calculate the probability, we need to know how many number have 5 digit number
21. To calculate the probability, we need to know how many number have 5 digit number Exclude 0 because if 0 lay at 1 st position, it will make the number with 4 digit. 9
22. To calculate the probability, we need to know how many number have 5 digit number 9 Exclude 0 because if 0 lay at 1 st position, it will make the number with 4 digit. 10 10 10 10 The number can be 0 and repeated
23. To calculate the probability, we need to know how many number have 5 digit number x x x x 9 Exclude 0 because if 0 lay at 1 st position, it will make the number with 4 digit. 10 10 10 10 The number can be 0 and repeated = 90000 Multiply it, we will have the total number have 5 digit numbers
