# I am a 3-digit number. all three digits are different. my first and second digits are multiples of 3. my third digit is greater than 3. the sum of my first two digits is 7 more than the third digit. iam not a multiple of 5. what number am i?

1
by gtmansueto

2015-10-11T12:28:20+08:00
"My first and second digits are multiples of 3"
So there first and second digit maybe one of the following: 3, 6, 9

"The sum of my first two digits is 7 more than the third digit"
"D1 + D2 = 7 + D3"

"Not a multiple of 5"
means it is not ending with "5" or "0"

If D1 = 6
If D2 = 9
D3 = ?
"6 + 9 = 7 + x"
NOTE: x = digit no. 3

15 = 7 + x
15 - 7 = 7 - 7 + x
8 = x

The number is:
698

3 digit number - CHECK
3 digits are different - CHECK
1st and 2nd digit is multiple of 3 - CHECK
3rd digit is greater than 3 - CHECK
The sum of my first two digits is 7 more than the third digit - CHECK
( 6 + 9 = 7 + 8)
(15 = 15)
Not a multiple of 5 - CHECK

So therefore, the number is 698, it can also be 968 as well.

I get it by combining some multiples of 3 (3, 6, and 9,) and I come up with 6 and 9 MATCHING ALL THE REQUIREMENTS.
I tried 3 and 6, 3 and 9, but they failed.
:)

*EDITED*
Thank you. It really helped alot.
:D
It's nice to help you and you're welcome. I am bad at math last time XD but because of brainly... :)