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In this lesson, we will learn how to use the decomposition of teen numbers into tens and ones to help subtract 7, 8, or 9 from numbers between 11 and 20.
Q1:
Which addition expression is equal to ?
Q2:
Think about taking away 9 from different numbers.
For example, the pictures show that 10 take away 9 is 1 and 11 take away 9 is 1 + 1 .
Look at these number sentences. Which one is WRONG?
Q3:
Sherif is baking cupcakes. He has 10 cupcakes cooling on the table, and 7 cupcakes in the oven. He puts icing on 9 of the cupcakes on the table. If all the cupcakes need to be iced by the end of the day, how many more cupcakes does he need to ice?
Q4:
Let us try to find 13 take away 9.
We can draw 13 dots as one group of 10 dots and one group of 3 dots.
Now take away 9 from the group of ten dots.
We are left with 1 + 3 dots which is 4 dots.
So 1 3 – 9 = 4 .
Now you have a go. What is 1 2 – 9 ?
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