Today was all about subtracting.
We demonstrated how and why subtraction works the way it does by looking at whether we had to regroup (borrow) from the place value number to the left of the number we were wanting to subtract with:
34 2
- 1 7 1
Here you can take 2-1 = 1 in the ones place value, but when you get the to the tens place value, you're unable to take 7 from 4.
You would end up with a negative number, which doesn't work. Instead, you have to regroup one group of one hundreds over to the tens place value:
We demonstrated how and why subtraction works the way it does by looking at whether we had to regroup (borrow) from the place value number to the left of the number we were wanting to subtract with:
34 2
- 1 7 1
Here you can take 2-1 = 1 in the ones place value, but when you get the to the tens place value, you're unable to take 7 from 4.
You would end up with a negative number, which doesn't work. Instead, you have to regroup one group of one hundreds over to the tens place value:
 |  |
After you regroup, you can solve the rest of the equation:
Practice, practice, practice. Roll the dice to make up numbers, write them down, and solve to find the difference between them.
The Khan Academy has a great series of video tutorials you can look at for extra practice at home, too!
Subtracting 3-digit numbers (regrouping)
See you tomorrow,
Ms. H
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