I AWARD MEDALS!!!
Can someone please show me the steps to solving this?? I have no clue
Each level of a smartphone app adds more gems for you to match. On level one, there were 13 gems. On level twelve, there were 123 gems. When you complete all twelve levels, how many total gems will you have matched?

Question

I AWARD MEDALS!!! 
Can someone please show me the steps to solving this?? I have no clue
Each level of a smartphone app adds more gems for you to match. On level one, there were 13 gems. On level twelve, there were 123 gems. When you complete all twelve levels, how many total gems will you have matched?

gorv · Answer

level 1= 13
level 12= 123
total gems added=123-13=110 in 11 levels(2nd  3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th level ...total 11 level)
so gems added on each level= 110/11=10 gems on each level

gorv · Answer

so add gems of each level
ist=13
2nd=13+10
3rd=13+10 +10
.......
.
.
.
.
.
.
.
11th= gems on 10th level +10
12th=123
add all of them=matchedgems

anonymous · Answer

I got 803 but that isn't an option

anonymous · Answer

@gorv

gorv · Answer

13+23+33+43+53+63+73+83+93+103+113+123=816

gorv · Answer

i think u forgot to add ist level=13

anonymous · Answer

Oh! Yeah. sorry. Thank you!