Today we reviewed borrowing in subtraction.
We looked at why we borrow by modeling with base ten blocks.
Then we learned about "counting - up" method of subtraction.
Think about when you get change back from a store.
The clerk counts up.
The clerk counts up.
If the total due is $1.80 and you pay with 2 $1.00 bills.
The clerk should say. $1.90 as she/he places a dime in your hand,
$2.00 as she/he places a second dime in your hand.
The change back to you is $0.20.
Take this concept and apply it to all subtraction as an alternate way to subtract.
63 - 37 = ?
Start with the lowest number and count up until you reach the biggest number:
37 +3 = 40
40 +20 = 60
60 +3 = 63
now: add all of your "count ups"
+ 3 +20 +3 = 26
answer: 26
Math is just puzzles waiting to be solved.
Remember there are sometimes more than
one way to reach the correct answer!
Not all minds think alike.
This might not be "your" easiest way to solve
but it might be your neighbor's!
Let's give it a try!
752 - 387 =
387 +3 = 390
390 +10 = 400
400 +300 = 700
700 +52 = 752
now add up your "count ups"
+3 +10 +300 +52 = 365
Remember take as many steps as you need, just don't forget to add them ALL up at the end!
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