## BDMO National Junior 2018/7

nahin munkar
Posts: 81
Joined: Mon Aug 17, 2015 6:51 pm
Location: banasree,dhaka

### BDMO National Junior 2018/7

All possible \$4\$ digit numbers are created using \$5,6,7,8\$ and then sorted from smallest to largest. In the same manner, all possible \$4\$ digit numbers are created using \$3,4,5,6\$ and then sorted from smallest to largest. Then first number of the second type is subtract from first number of the first type, second number of the second type is subtract from second number of the first type and so on. What will be the summation of these difference (subtraction results) ?
# Mathematicians stand on each other's shoulders. ~ Carl Friedrich Gauss

samiul_samin
Posts: 1007
Joined: Sat Dec 09, 2017 1:32 pm

### BdMO National Junior problem 7

You can get the problem here
Short solution

prottoy das
Posts: 17
Joined: Thu Feb 01, 2018 11:28 am
Location: Sylhet

### Re: BDMO National Junior 2018/7

Probably it will be \$4^4\$ permutations. Because here, it is not said that a digit will be written one time in a number

samiul_samin
Posts: 1007
Joined: Sat Dec 09, 2017 1:32 pm

### Re: BDMO National Junior 2018/7

prottoy das wrote:
Wed Jan 16, 2019 11:22 pm
Probably it will be \$4^4\$ permutations. Because here, it is not said that a digit will be written one time in a number
I really missed that