1. If the sum of positive integers $a$ and $b$ is $n$, then $n$ can be transformed into $a b$. Can this method be used several times to change 22 into 2001?
1. Reverse calculation, $2001=3 \times 667$ from $3+667=670$; $670=10 \times 67$ from $10+67=77$; $77=7 \times 11$ from $7+11=18$. From any $n=1+(n-1)$, we can get $n-1=1 \times(n-1)$. Therefore, starting from 22, we can sequentially get 21, $20,19,18,77,670$ and 2001.