Checking Exact Change

"Count your money before you leave." A friendly reminder when you are paying at the cashier or in vendor's stand. Check the exact change by mastering "All from 9, Last from 10."

Example:
You hand 1000 Php bill for payment of goods worth 648 Php. How much is the exact change? Know the exact change without the aid of calculators.

Just deduct all the digits from 9 and the last non-zero digit from 10.
1000 - 648 = ?
9 - 6 = 3
9 - 4 = 5
10 - 8 = 2
1000 - 648 = 352

Or you can think of it this way:
1000 - 648 = ?
   9  9  10
 - 6  4  8  
   3  5  2   answer

Or simply think of a number that will complete the digits into 9 9 10.
 1000 - 468 = ?
 6 4 8 
 3 5 2 answer

More examples:
 100 -78 = ?
 7 8 
 2 2 answer

 1000 - 385 = ?
 3 8 5 
 6 1 5 answer

 1000 - 740 = ?
   9 10 0           (10 for last non-zero)
- 7  4  0  
  2  6  0   answer

1000 - 407 = ?
   9  9 10
- 4  0  7   
  5  9  3  answer

#Matamata