Comparative Relational Thinking Multiplication Lets Review Are these

Comparative Relational Thinking Multiplication

Let’s Review Are these equations true or false? 432+ +129 234= =566 440+ +130 240 567 How do you know the equation is true? TRUE FALSE

Let’s Review Fill in the blank 93 + 27 = __ + 20 Talk me through your thinking. 100

Let’s Review What strategies do you use to multiply? Break Repeated Apart Addition Doubling and Halving Draw Pictures Partial Products

Why does Doubling and Halving work? Let’s think about an easy problem. If I take half of the cubes, and Iput have 4 columns them at the and 12 rows. bottom of the The what rows array, DOUBLE to andthe happens columnsofare cut amount rows I will use the I havein 8 HALF! columns and columns? draw an array and 6 rows. strategy first! 8 x 6 8 x 6 = 48 4 x 12 = 48

Let’s Double and Half again…. 8 x 6 8 x 6 = 48 4 x 12 = 48 2 x 24 = 48 I have 2 4 columns and 24 12 rows.

Think about using Doubling and Halving to multiply… ÷ 2=7 X 2= 10 14 x 5 The answer is 70! Then I multiply If Ilook divide 14 by forto the 7 I Ican and 10 find divide 14 2, then I need even factor product. by 2. multiply 5 by 7 xfirst… 10= 70 2.

Think about using Doubling and Halving to multiply… X 3 = 72 ÷ 3=1 24 x 3 Do I always have to use 2? The answer is 72! Then I multiply If. No, I divide 3 by I can look 13, find then I to need I and can divide 3 for a 72 factor the product. multiply 24 by by that I 3. can 1 x 72= 72 divide 3. easily…

Using Doubling and Halving in Comparative Relational Thinking x 2 = 256 Let’s determine if this equation is TRUE or FALSE. Change one x 2 128 x 4 = 256 If you divide 4 by 2, factor on one you x 2 need ÷ 2 to multiply side 2 toand match the 128. 256 other x 2 = side. 256 x 2 ÷ 2=2 128 x 4 = 256 x 2 I don’t want to solve… BOTH factors So, I can 128 divide x 2 MATCH, is 4 by 2 I just want to 200 so+itto 40 isget +TRUE!!! 16 2? = 256. COMPARE

True or False? 36 x 4 = 2 x 62

True or False? 86 x 6 = 258 x 2

Find the missing factor. 32 x 5 = ___ x 1