NOT ALL DIGITS appear in the alphametic:
NOT*ALL= DIGITS
So, after solving it just check whether
SO*ITGT
is indeed
SOLID+GOLD
BTW, what digit is missing?
It turns out that the first equation has three solutions:
NOT*ALL=DIGITS
803*644=517132
327*488=159576
459*788=361692
Only the first solution also satisfies the second equation:
SO*ITGT=SOLID+GOLD
20*1373=20415+7045
Then the missing digit is 9.