Transcript Partial Sums Powerpoint

Partial Sums
• When students begin to learn how to add twodigit numbers they are usually taught “carrying”.
• A different way to do this is called the “Partial
Sums” algorithm.
• Partial sums focuses on place value when
solving two-digit addition problems.
• It teaches children to start on the left and add
the tens first.
• Moving from left to right (just like in reading!)
actually makes sense to the children and they
have a better understanding of why and how
they get their answer.
• Here is an example of the Partial Sums
Algorithm:
45
+38
7 0 Step 1: Add the tens (40 + 30 = 70) and write the sum.
+ 1 3 Step 2: Add the ones (8 + 5 = 13) and write the sum.
8 3 Step 3: Add the tens and ones
(70 + 13 = 83) to get the final answer.
• Here is another example of the
Partial Sums Algorithm:
67
+4 5
100 Step 1: Add the tens (60 + 40 = 100) and write the sum.
+1 2 Step 2: Add the ones (7 + 5 = 12) and write the sum.
112 Step 3: Add the tens and ones
(100 + 12 = 112) to get the final answer.
• http://www.youtube.com/watch?v=4UexB
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