Sum a list of 50 digit numbers

Problem 13 is summing a list of fifty digit numbers. I used the gmp library and R to solve in 2 lines:

library(gmp)
print(substring((sum(as.bigz(readLines("euler13.txt")))), 0, 10))

Not much more to say really. I forgot the problem asks for the first 10 digits, so my first answer was wrong.

Asus X541S

My wife’s laptop is an Asus X541SA – a fairly generic and inexpensive workhorse. With a Quad-Core N3710, 4Gb of RAM and a 1TB HDD. Unfortunately its ridiculously slow. Opening, switching and closing applications leaves time to make a cup of tea and clicking save in Word is likely to see a “(not responding)” caption in the title bar.

A quick look in task manager shows the HDD is perpetually at 100%. Having already tried a clean install of Windows 10, I figured an SSD might help. I got this 120 Gb SanDisk SSD, having used them before with good results.

What a difference it makes, the laptop is not only usable but responsive. While I doubt it would handle many games it can at least cope with Office and Firefox, which it couldn’t before.

Flashing Nexus 9 factory image

This tablet was super fast when I got it but now it lags and drives me nuts. I’d seen someone post on Reddit that flashing the factory image helped so I gave it a go.

Factory images are available here along with good, clear instructions. One caveat, Arch needs super user for fastboot otherwise you get “< Waiting for device >”. For the same reason run flash-all.sh with sudo too.

As to whether or not it helped, it is hard to say but I feel it has. How do you measure something that is entirely subjective?

Edit. Its been a few days now and it is faster. Much faster and without lag. I’m unclear why though. I’m not completely familiar with Android’s architecture but wonder if it’s a combination of multiple updates being applied (this was I think Android 5.0 when bought) and accumulated futz.

Some thoughts on Wireless charging

I bought an Anker PowerPort Qi 10 inductive charger from Amazon (£13.99). I’ve seen a few people online complaining that it isn’t “wireless charging” because it’s still “plugged in” – a farcical complaint akin to suggesting that the device draw current from the ether.

Without doubt one of the most convenient devices I’ve used – put your phone on it and off it goes. The only things that are worth bearing in mind are that you need to use a fast charger if you want it to fast charge.