The two basic operations are addition (+) and subtraction (−).
Adding
Add the ones, then add the tens. For example, 23 + 15: add the ones (3 + 5 = 8) and the tens (20 + 10 = 30), giving 38.
Subtracting
Take away one number from another. For example, 40 − 12 = 28.
Remember
- Addition puts numbers together; subtraction takes away.
- Line up the tens and ones neatly.