Answer:
2160
Step-by-step explanation:
I find that it is easier to split the sequence into smaller, more manageable sections. For numbers beyond 13, the simplest way is to split it up into place values.
Note: * is a multiplication symbol
5*1 = 5
5*8 = 40
5*27 = (5*20) + (5*7) = 100+35 = 135
5*64 = (5*60) + (5*4) = 300+20 = 320
5*125 = (5*100) + (5*20) + (5*5) = 500+100+25 = 625
5*216 = (5*200) + (5*10) + (5*6) = 1000+50+30=1080
Now you can add all of the totals up!
135+320+625+1080 = 2160
