Question

Find the sum of 4 digits formed by taking all the digits 1 2 5 7

Answer 1

Answer:

99990

Step-by-step explanation:

Using all 4 digits 1 , 2, 5 & 7

the number of 4 digits we can form

= 4 * 3 * 2 * 1 = 24

1257

1275

1527

1572

1725

1752

2157

2175

2517

2571

2715

2751

5127

5172

5217

5271

5712

5721

7125

7152

7215

7251

7512

7521

Sum of these numbers = 99990

other wise as we know that

in 24 Nmbers  each digits will be used 24 times

(6 times at units place + 6 times at 10's Place + 6 time at 100's Place + 6 time at 1000's Place)

Sum at Each unit's place = 6 * ( 1+ 2 + 5 + 7) = 90

So Sum of all numbers would be

90*1000  + 90*100 + 90*10  + 90*1

= 90000 + 9000 + 900 + 90

= 99990