Mathematical trick

Trick 3 : Group In to Twos
Same idea applies to subtraction, what's easier to think about, 15528-1210 or:


It's easier to think “28-10=18” and “55-12=43”

Carries still apply as normal:
4812 - 1598


A bit like school, 12 – 98, make it 112 – 98 = 14 carry one

1

Do 48-15 then subtract one, 48-15=33, 33 – 1 = 32