Ummmm.. my head is spinning. I keep a slim pocket sized calculator in my shirt pocket.
In the unlikely event that high G forces prevent me from reaching it.
14 x 13 .... 2(7 x 13)
16 x 17..... 4(4 x 17)
15 x 13 .... 3(5 x 13)
12 x 13 .... (12 x 12) + 13
13 x 13 .... (10 x 13) + (3 x 13)
18 x 51 .... (50 x 18) + 51 .... 10(5 x 18) + 51
68 x 72 .... (60 x 72) + (8 x 72)
OK I admit it, right after 18 x 51 , I crashed !!!
I think we all find a way that suits us in the end
Regards,
Paul.