p&cq12

[Saumyojit]

How many seven-digit nos can be formed whose digit sum is equal to 10 and is formed by using only the digits 1, 2 and 3

Total there are 3^7=2187 seven digit numbers out of which some of them results to 10.

 

[Deleted member 4993]

How many seven-digit nos can be formed whose digit sum is equal to 10 and is formed by using only the digits 1, 2 and 3

Total there are 3^7=2187 seven digit numbers out of which some of them results to 10.

Do you know the answer to the posted problem -

where did it come from? Is the answer a multiple choice?​

If we choose five 1 's, we need to have 3 and 2 for the other two spaces. How many numbers can you create out of that set?

 

[Eugenio]

If the number has a 3, then it needs a 2 so it forms 3211111 and its permutations, that is $$\frac{7!}{5!}=42$$And if you don't have 3, then it must be 2221111 and its permutations. $$\frac{7!}{3!4!}=35$$So, there are 77 possible combinations