Plotting values like 1.10e15, 1.3e15, 2e15 using ggplot or spplot

i am tring to plot data, which range in 1e15-2e15, unfortunately i am not able to plot a nice line graph.How to make y-axis to be abbreviated into 1e15 instead of 1000000000000000in graph

>library(readxl)
>library("xlsx")
>library(ggplot2)
>test <- read.xlsx2("/filepath/", 3, header=TRUE)  
>ggplot(test,aes(x=NO2, y=  SA)) + geom_point()