pick length 8 > [
2drop 10 digits>integer
] [
- [ * number>digits over push-all ] 2keep 1+ (concat-product)
+ [ * number>digits over push-all ] 2keep 1 + (concat-product)
] if ;
: concat-product ( n -- m )
! [ euler038 ] 100 ave-time
! 11 ms ave run time - 1.5 SD (100 trials)
-MAIN: euler038
+SOLUTION: euler038