Explanation. Standard caveat: don’t look here if you are trying to do these yourself.
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. Find the sum of all the multiples of 3 or 5 below 1000.
This one’s pretty straight forward, really, as one might hope being the first question. R’s built-in subsetting mechanism handles the extraction fairly nicely. I perhaps would have liked a way to do this without first defining x; though I suppose it could just be repeated in the last line.
## check the worked solution
sum(c(3,5,6,9))## [1] 23## values < 1000
x <- 1:999
## sum of x % 3 or x % 5
sum(x[x %% 3 == 0 | x %% 5 == 0])## [1] 233168### CORRECT
devtools::session_info()
## ─ Session info ──────────────────────────────────────────────────────────
## setting value
## version R version 3.5.2 (2018-12-20)
## os Pop!_OS 19.04
## system x86_64, linux-gnu
## ui X11
## language en_AU:en
## collate en_AU.UTF-8
## ctype en_AU.UTF-8
## tz Australia/Adelaide
## date 2019-08-13
##
## ─ Packages ──────────────────────────────────────────────────────────────
## package * version date lib source
## assertthat 0.2.1 2019-03-21 [1] CRAN (R 3.5.2)
## backports 1.1.4 2019-04-10 [1] CRAN (R 3.5.2)
## blogdown 0.14.1 2019-08-11 [1] Github (rstudio/blogdown@be4e91c)
## bookdown 0.12 2019-07-11 [1] CRAN (R 3.5.2)
## callr 3.3.1 2019-07-18 [1] CRAN (R 3.5.2)
## cli 1.1.0 2019-03-19 [1] CRAN (R 3.5.2)
## crayon 1.3.4 2017-09-16 [1] CRAN (R 3.5.1)
## desc 1.2.0 2018-05-01 [1] CRAN (R 3.5.1)
## devtools 2.1.0 2019-07-06 [1] CRAN (R 3.5.2)
## digest 0.6.20 2019-07-04 [1] CRAN (R 3.5.2)
## evaluate 0.14 2019-05-28 [1] CRAN (R 3.5.2)
## fs 1.3.1 2019-05-06 [1] CRAN (R 3.5.2)
## glue 1.3.1 2019-03-12 [1] CRAN (R 3.5.2)
## htmltools 0.3.6 2017-04-28 [1] CRAN (R 3.5.1)
## knitr 1.24 2019-08-08 [1] CRAN (R 3.5.2)
## magrittr 1.5 2014-11-22 [1] CRAN (R 3.5.1)
## memoise 1.1.0 2017-04-21 [1] CRAN (R 3.5.1)
## pkgbuild 1.0.4 2019-08-05 [1] CRAN (R 3.5.2)
## pkgload 1.0.2 2018-10-29 [1] CRAN (R 3.5.1)
## prettyunits 1.0.2 2015-07-13 [1] CRAN (R 3.5.1)
## processx 3.4.1 2019-07-18 [1] CRAN (R 3.5.2)
## ps 1.3.0 2018-12-21 [1] CRAN (R 3.5.1)
## R6 2.4.0 2019-02-14 [1] CRAN (R 3.5.1)
## Rcpp 1.0.2 2019-07-25 [1] CRAN (R 3.5.2)
## remotes 2.1.0 2019-06-24 [1] CRAN (R 3.5.2)
## rlang 0.4.0 2019-06-25 [1] CRAN (R 3.5.2)
## rmarkdown 1.14 2019-07-12 [1] CRAN (R 3.5.2)
## rprojroot 1.3-2 2018-01-03 [1] CRAN (R 3.5.1)
## sessioninfo 1.1.1 2018-11-05 [1] CRAN (R 3.5.1)
## stringi 1.4.3 2019-03-12 [1] CRAN (R 3.5.2)
## stringr 1.4.0 2019-02-10 [1] CRAN (R 3.5.1)
## testthat 2.2.1 2019-07-25 [1] CRAN (R 3.5.2)
## usethis 1.5.1 2019-07-04 [1] CRAN (R 3.5.2)
## withr 2.1.2 2018-03-15 [1] CRAN (R 3.5.1)
## xfun 0.8 2019-06-25 [1] CRAN (R 3.5.2)
## yaml 2.2.0 2018-07-25 [1] CRAN (R 3.5.1)
##
## [1] /home/jono/R/x86_64-pc-linux-gnu-library/3.5
## [2] /usr/local/lib/R/site-library
## [3] /usr/lib/R/site-library
## [4] /usr/lib/R/library