Question

the sum of all odd numbers of four digits which are divisible by 9

Answer 1

The four digit numbers which are divisible by 9 are are 1017,1035,1053,.....................,9999

Here, a = 1017, d = 9 ,and tn = 9999

Therefore, tn = a + ( n - 1 ) d
9999 = 1017 + ( n - 1 ) 9
9999 - 1017 = 9n - 9
9n = 9999 - 1017 + 9
9n = 8973
n = 8973 ÷ 9
n = 997...

Now, sum of all odd numbers of four digits numbers divisible by 9 ,

a = 1017 , d = 9 , n = 997
Therefore, Sn = n÷2[ 2a + ( n - 1 ) d ]
Therefore, S-997 = 997÷2 [ 2×1017 + ( 997 - 1 ) ×9 ]
S-997 = 997÷2 [ 2034 + 996×9 ]
S-997 = 997÷2 [ 2034 + 8964 ]
S-997 = 997÷2 [ 10998 ]
S-997 = 997 × 5499
S-997 = 5482503.......

Therefore the sum of all odd number of four digits divisible by 9 is 5482503.

Answer 2

Hey friend !!

I got answer as -2754000-

Hope it helps

if correct please mark as brainliest!!