Pleased to see that Christian had also answered Jon's call and I had bested him for the first time in a while!I'm going to meet Christian at the boathouse today. Maybe I can persuade him to have another go Great row by the way

Statistics: Posted by

There are some tricks of course.

Divisors will therefore always be odd numbers except for 5.I'm presently around 701k and planning a session today which means heading for 712023 or 712033.It is only necessary to divide by primes as (assuming you start at the bottom) any non-prime factor will have already been revealed from dividing by the prime factor of the multiple firs...

Congratulations to Kevin Horne for reaching two million meters for the seaon!

Statistics: Posted by Grobi — Wed Apr 22, 2026 9:04 am

Agreed Ian - it's an exercise in mental arithmetic that gets harder as you get physically more tired.

There are some tricks of course.

All primes (except 2 and 5) end in 1,3,7 or 9.

Divisors will therefore always be odd numbers except for 5.

For those with a mathematical (as opposed to an arithmetic) mind, there about a dozen of so theories about how...

I like your thinking. That said, it took me 20 min to factorise FM and HM while walking (I was tired and needed to cross multiple busy roads so got distracted) and find my mental arithmetic is better than most so no chance that for a significant number that I could do this while erging, especially if the target changed, so would need to set the distance before I started. I can s...