Subtracting means taking away
You have 9 grapes and you eat 4. How many are left? Count back four from 9: 8, 7, 6, 5. There are 5 left.
9 − 4 = 5
Say it as "9 take away 4 is 5."
Another way: count up
Subtraction also tells you how far apart two numbers are. For 52 − 48, counting back 48 steps would take forever. Count up from 48 instead: 49, 50, 51, 52. That's 4 steps, so 52 − 48 = 4.
When the two numbers are close together, counting up is the easy way.
You can always check with adding
Subtraction is addition backwards. If 9 − 4 = 5, then 5 + 4 should make 9. It does, so the answer is right. Check this way whenever you're not sure.
Bigger numbers: tens and ones
For 47 − 23, take away the ones and the tens separately. 7 ones take away 3 ones is 4 ones. 4 tens take away 2 tens is 2 tens. The answer is 2 tens and 4 ones: 24.
What borrowing really is
Now try 52 − 27. Start with the ones: 2 take away 7. You can't, because 2 is too small.
So trade. 52 is 5 tens and 2 ones. Break one of the tens into 10 ones. Now you have 4 tens and 12 ones. It is still 52, just arranged differently.
- Ones: 12 − 7 = 5
- Tens: 4 − 2 = 2
- Answer: 2 tens and 5 ones = 25
Check it: 25 + 27 = 52. That trade is all "borrowing" or "regrouping" means. You are swapping one ten for ten ones so there's enough to take away from.
When there are zeros on top
Problems like 100 − 36 are the hardest to borrow on paper. Counting up is easier. From 36 to 40 is 4. From 40 to 100 is 60. Add the jumps: 4 + 60 = 64.
Try it with real things
Use dimes for tens and pennies for ones. Lay out 5 dimes and 2 pennies, then try to take away 27 cents. You'll have to swap a dime for ten pennies. Doing the trade with your hands is the quickest way to make borrowing make sense.
A hundred chart helps too: move up a row to take away 10, and left to take away 1.
Practice without anyone watching
Fun With Learning is a free app with no ads and nothing to buy. Borrow Power shows the trade happening, and Hop Back shows subtraction as jumps on a number line. There are no timers, and hints walk through a problem step by step. See the math games and activities.
