Everyone works differently in mental meth.
To calculate 9*52, we note that 9=10-1, so mentally calculate
9(52)
=(10-1)(52)
=520-52 [ subtract 20 from each number]
=(520-20)-(52-20)
=500-32
=468.
Alternatively,
9*52=9*50+9*2=450+18=468
If you're good with multiplication and division,
9*52=3*3(52)=3*156=450+18=468