Two Digit Addition

Today we learned two new strategies for adding two digit numbers. Before, we've been drawing the hundred block, ten rods, or ones.

Now we want to work on faster strategies. Hopefully, my kiddos understand the concept of base ten. So we can move on to more mental strategies.

Partial Sums Video

Partial Sums means that you add the tens first, then the ones, and add those sums together.
Example: 43 + 20 becomes 40+20, 3+5 and then 60+8.

Friendly Numbers Video

Friendly number means that you change one of the addends to be a number that ends in zero.
Example 53+29 becomes 52+30.

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