Use the formula ALL FROM 9 AND THE LAST FROM 10 to perform instant subtractions.
We simply take each figure in 357 from 9 and the last figure from 10.
So the answer is
1000 - 357 = 643
And thats all there is to it!
This always works for subtractions from numbers consisting of a 1 followed by
noughts: 100; 1000; 10,000 etc.
So 1000 - 83 becomes 1000 - 083 = 917