Multiply by Multiples of 10

Transcription

1 Multiply by Multiples of 10 Home-School Connection Topic 10 Dear Family, Your child is learning to apply his or her knowledge of place value to multiply greater numbers. By looking for patterns in multiplication facts, he or she will learn to multiply multiples of 10 by one-digit numbers using mental math. Here are some examples of patterns that your child is learning: Your child is also learning how multiplication properties can help him or her multiply by multiples of 10. You can group factors using the Associative Property of Multiplication (2 10) (5 2) You can decompose a factor using the Distributive Property (3 + 2) 20 (3 20) + (2 20) Multiplying with 2-Digit Numbers Give your child a one-digit by two-digit multiple of 10 multiplication problem, such as Have your child solve the problem by either grouping the factors or by decomposing a factor. For example, you can group the factors. Or you can decompose a factor (4 10) 4 40 (2 + 2) 40 (4 4) 10 (2 40) + (2 40) Observe Your Child Have your child use an open number line to show the multiplication problems he or she worked on.

2 Nombre Multiplicar por múltiplos de 10 De la escuela al hogar (en español) Tema 10 Estimada familia: Su niño(a) está aprendiendo a usar lo que aprendió sobre el valor de posición para multiplicar números más grandes. Al buscar patrones en operaciones de multiplicación, aprenderá a multiplicar mentalmente múltiplos de 10 por números de un dígito. Estos son algunos ejemplos de los patrones que está aprendiendo su niño(a) Su niño(a) también está aprendiendo a usar las propiedades de la multiplicación como ayuda para multiplicar por múltiplos de 10. Se puede usar la propiedad asociativa de la multiplicación para agrupar factores (2 10) (5 2) Se puede usar la propiedad distributiva para descomponer un factor (3 + 2) 20 (3 20) + (2 20) Multiplicar con números de 2 dígitos Dé a su niño(a) un problema de multiplicación de un número de un dígito por un múltiplo de 10 de dos dígitos, como Pídale que agrupe los factores o que descomponga un factor para resolverlo. Por ejemplo, se pueden agrupar los factores. O se puede descomponer un factor (4 10) 4 40 (2 + 2) 40 (4 4) 10 (2 40) + (2 40) Observe a su niño(a) Pídale que represente los problemas de multiplicación que resolvió en una recta numérica vacía.

3 Vocabulary 1. You can use an open number line to multiply by multiples of 10. Reteach to Build Understanding 10-1 How many jumps are on the number line? jumps How long is each jump? Use the number line to find Complete the products in the table. Use an open number line to help jump of 20 is jumps of 20 is. 3 jumps of 20 is. 4 jumps of 20 is. 5 jumps of 20 is. Factor Multiple of 10 Product The pattern in the product column is similar to the pattern when you multiply by 2, but with a 0 in the ones place. 3. Use an open number line to find Show 4 jumps of 50 on the number line jumps of 50 is On the Back! 4. Draw and label an open number line to find the product of R 10 1

4 Rose Garden Math and Science Activity 10-1 Did You Know? The thorns on the stem of a rose are actually called prickles. Sharp points are used by a variety of plants for defense in the wild. Prickles come in different lengths, colors, and shapes. In addition to its prickles, the rose also uses its smell as a defense tool. Liu and Kumar work at a rose garden. Liu finds that all of the full-grown rose bushes each have 30 prickles. There are 8 full-grown rose bushes. Use the questions below to complete the number line. ➊ Liu wants to use an open number line to find the total number of prickles. Liu should use jumps of. ➋ How many jumps should Liu complete? ➌ Complete the number line. 8 jumps of 30 is. 0 ➍ The rose garden receives 2 more full-grown rose bushes, each with 30 prickles. Explain how Liu should change her number line to show this. How many total prickles are there now? ➎ Extension Kumar says, 3 10 is 3 groups of 1 ten. 3 times 10 equals 30. Write sentences to describe in a similar way. Math and Science Activity 10 1

5 Vocabulary Reteach to Build Understanding You can use the Associative Property of Multiplication to group factors. The way factors are grouped does not change the product. Find the product of in two different ways (3 2) (2 5) You can use the Distributive Property to decompose a factor. A multiplication fact can be broken apart into the sum of two other multiplication facts. Find (3 + 4) 5 + (3 5) + (4 5) 3. Find Use the Associative Property of Multiplication to group factors (6 ) (7 ) Find Decompose a factor. Write 4 as (2 + ) 80 (2 ) + (2 ) + On the Back! 5. Find 5 90 using properties of multiplication. Show your work. R 10 2

6 Vocabulary Reteach to Build Understanding A multiple is the product of a given whole number and any nonzero whole number. Find the multiples of Some multiples of 10 are 10, 20,,,. 2. Use the Associative Property of Multiplication to find ( 10) (6 ) 3. Use a shortcut to find Multiply by the digit in the tens place. 7 Write one zero after the product. So, Use a shortcut to find each product. 9 40? 60 5? 2 80? On the Back! 5. Find 7 90 using the Associative Property of Multiplication. Show all the steps in your work. Then, use the shortcut to find the same product. R 10 3

7 Crab Legs Math and Science Activity 10-3 Did You Know? Some animals have 8, 10, 30, or even 600 legs. Shrimp and crabs have 10 legs, which help them easily navigate the ocean water and floor. Crabs and shrimp use their legs to help them avoid prey. Animals that have 10 legs are called decapods. A group of crabs is called a cast. Ms. Zaizar is studying casts of crabs in the science laboratory. ➊ Ms. Zaizar s laboratory has 4 tanks. In each tank there are 80 crab legs. How many crab legs are there in all of the tanks? ➋ Explain how Ms. Zaizar can represent this problem on an open number line. ➌ How many crabs are in each tank? Explain. ➍ Extension Ms. Zaizar acquires 2 more tanks with 8 crabs in each tank. Write equations to find the number of crab legs in all of the tanks. Math and Science Activity 10 3

8 Vocabulary 1. Factors are numbers that are multiplied together to give a product. The multiplication table shows that The factors are and. The product is. Reteach to Build Understanding Complete the equations. One factor is always a multiple of ten. Multiply by the digit in the tens place and write one zero after the product. Then complete the table Complete the table. Think about patterns or properties you know for multiplying by multiples of As you move down the columns, the numbers value of the column. by the On the Back! 4. Carla wants to make either 5 or 6 batches of cookies. She is choosing whether to use 40, 50, or 60 chocolate chips for each batch. Complete a table to show the total number of chocolate chips Carla will need for each choice. R 10 4