TRICK TO SUBSTRACT NUMBER EASILY

this is an easy trick
To subtract a large number from 1,000
subtract all but the last number from 9, then subtract the last number from 10

1000
-547

step1: subtract 5 from 9 = 4
step2: subtract 4 from 9 = 5
step3: subtract 7 from 10 = 3

answer: 453