Question

The number 2006 is made up of exactly two zeros and two other digits whose sum is 8. The number of 4 digit numbers with these properties (including 2006) is
21 is answer how???.

Answer 1

the 21 numbers are

1007 1070 1700

2006 2060 2600

3005 3050 3500

4004 4040 4400

5003 5030 5300

6002 6020 6200

7001 7010 7100

Answer 2

Step-by-step explanation:

the number of probability that 0,9 and 8will be used is zero and rest all numbers can be use and have three uses

eg: 2006,2060,2600.......

so multiple of 3 by digits used =21

1-3

2-3

4-3

5-3

6-3

7-3

×

--------

21