|Here's how we're going to do it:
Now, remember, that's really 90 = 80 + 10!
Now, here's the key to this whole trick:
A 1 in the tens stripe is 10...
and that's the same as 10 ones!
< It's just like swapping a $10 bill for ten $1 bills! >
Now, add the 10 and the 2 in the ones stripe:
Now, we'll finish it off quick!
Subtract the ones... Then, subtract the tens...
Go to the next page for another one... It's going to feel a LOT easier the second time!