1 / 10

Doubling and Halving

Doubling and Halving. Double 4 is 8 and half of 18 is 9 so 8 x 9 = 72. Trebling and Thirding. Problem: If I planted 4 rows of strawberry plants and put 18 plants in each row how many plants would I have altogether?. Triple 4 is 12 and a third of 18 is 6 so 12 x 6 = 72.

uri
Download Presentation

Doubling and Halving

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Doubling and Halving Double 4 is 8 and half of 18 is 9 so 8 x 9 = 72 Trebling and Thirding Problem: If I planted 4 rows of strawberry plants and put 18 plants in each row how many plants would I have altogether? Triple 4 is 12 and a third of 18 is 6 so 12 x 6 = 72

  2. Rounding and Compensating Problem: If I planted 4 rows of strawberry plants and put 18 plants in each row how many plants would I have altogether? 20 x 4 = 80. However that’s 2 plants too many in each row so I need to take away 4 x 2 which is 8, so 80 – 8 = 72

  3. Place Value Partitioning Problem: If I planted 4 rows of strawberry plants and put 18 plants in each row how many plants would I have altogether? 18 x 4 is the same as 10 x 4 = 40 + 8 x 4 = 32 so 40 + 32 = 72

  4. Reversibility Problem: If I wanted to buy 72 cans of soft drink how many 6 packs would I need to buy? 12 x 6 is 72 therefore 72 ÷ 6 = 12

  5. Proportional Adjustment Problem: If I wanted to buy 72 cans of soft drink how many 6 packs would I need to buy? Half of 72 is 36 and half of 6 is 3 so 36 ÷ 3 = 12. A third of 72 is 24 and a third of 6 is 2. 24 ÷ 2 = 12.

  6. Divisibility Problem: If I wanted to buy 72 cans of soft drink how many 6 packs would I need to buy? I know 60 is a multiple of 6 and so is 12 so 10 + 2 = 12.

  7. Conversion and Commutativity Problem: I cut 24 metres of material into lengths of 0.75m. How many pieces do I have? 24 ÷ ¾ =  so ¾ x  = 24? If 24 is ¾ then ¼ must be 8. The answer is 8 x 4 = 32 pieces.

  8. Doubling and Halving with Place Value Problem: I cut 24 metres of material into lengths of 0.75m. How many pieces do I have? 24 ÷ 0.75 is the same as 48 ÷ 1.5 which is the same as 96 ÷ 3 = 32.

  9. Commutative operations in everyday life: Putting on shoes resembles a commutative operation, since which shoe is put on first is unimportant. Either way, the end result (having both shoes on), is the same. The commutativity of addition is observed when paying for an item with cash. Regardless of the order in which the notes or coins are given, they always give the same total. Commutativity Addition: 7 + 4 is the same as 4 + 7 Multiplication: 8 x 3 is the same as 3 x 8

  10. Opposite operations are reversible: Division ( ÷ ) is the opposite of multiplication ( × ).Subtraction ( − ) is the opposite of addition ( + ). Reversibility 15 ÷ 3 = 5 can be reversed to 5 × 3 = 15 12 + 7 = 19 can be reversed to 19 − 7 = 12

More Related