TCS
Company
Logical Reasoning
Logical Sequences
8+88+888+.....+8888........8888. There are 21 “8” digits in the last term of the series.
Find the last three digits of the sum.
Read Solution (Total 6)
-
- 968 is the answer.
As their is 21 no of 8 will add in first summation then 20 and then 19.
so 21*8=168 from that 8 will come 16 as a carry
and 20*8=160 , 160 + 16 (carry from first term) = 176 and from that 6 will come 17 as a carry
at last 19*8=152 , 152+17=169 , so from that 9 will come
and answer become 968 - 9 years agoHelpfull: Yes(47) No(3)
- Simply add
In Unit Digit (8+8+8+....21times)=21*8=168
unit digit =8, carry =16
In tens Digit (8+8+8+....20times)=20*8=160+(16)=176
unit digit =6, carry =17
In hundred Digit (8+8+8+....19times)=19*8=152+17=169
unit digit =9, carry =16
so last three digits= 968 - 9 years agoHelpfull: Yes(29) No(0)
- there are 21 8's at unit digit which results to (21*8=168) 8 at the unit digit of the sum and 16 is the carry for tens digit number. there are 20 8's at tens digit that results to (20*8=160) 160+16(from the carry)=6 at the tens digit and now 17 is the carry. similarly for 100th place (19*8)results to 152+17 and digit is 9.
hence answer is 968. - 9 years agoHelpfull: Yes(4) No(0)
- answer is 968
- 9 years agoHelpfull: Yes(3) No(0)
- 21th term- 8888......888
20th term- 8888.......88
19th term- 8888.......8
--------------------------------
568
- 9 years agoHelpfull: Yes(0) No(9)
- 21*8= 168
21*7+16=163
21*6+16= 142
so the last three terms are 238 - 9 years agoHelpfull: Yes(0) No(5)
TCS Other Question