Answer:
C - 13*
Step-by-step explanation:
2*10^6 + 6*10^5 + 3*10^3 +9*10^1 +4*10^0
see expanded form is adding the digits together. and it would be what ever one number is times 10 to the power of how many digits are after that number. you skip the 0's though. hope this helps

if you have already covered slopes, you could also get it that way, in fact is simpler that way.