jag_Uppal wrote:Hi

Can somebody breakdown then answer for me for question 2 of chapter 1? I can't seem to understand the answer key.

Question is:

What is the sum of all possible 3-digit numbers that can be constructed using digits, 3,4 and 5 if each digit can be used onlyonce in each number?[/img]

I don't have the book and I don't know the answer choices, but I interpret the question as

345+354+453+435+534+543

jag_Uppal wrote:Hi

Can somebody breakdown then answer for me for question 2 of chapter 1? I can't seem to understand the answer key.

Question is:

What is the sum of all possible 3-digit numbers that can be constructed using digits, 3,4 and 5 if each digit can be used onlyonce in each number?[/img]

All possible 3-digit numbers are
345
354
435
....
....
....

i.e. each of the number - 3, 4, and 5 are getting repeated in the units/tens and hundreds place.

So 2(3+4+5) = 24

so the units digit is 4, 2 is carried over and is added to 24 (since the tens place also adds upto 24) to give 26, so tens place is 6, and 2 gets carried over to the hundred's place (24 again) to give 2+24 = 26.

Final number = 2664 (26 hundred's place, 6 tens place and 4 units place from above)