Expressions 4 th Grade Expressions An expression has

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Expressions 4 th Grade

Expressions 4 th Grade

Expressions • An expression has numbers and operation signs, but no equal sign. Expressions

Expressions • An expression has numbers and operation signs, but no equal sign. Expressions can include parentheses and different operations (+, -, x). • Sue had 12 flowers. Lily gave her 4 more flowers. Sue gave her teacher 3 of her flowers. How many does she have left? • 12 flowers plus 4 flowers, minus 3 flowers • (12 + 4) – 3 • 16 – 3 • 13

Expressions (Example A) • • • Find the value of (9 – 5) +

Expressions (Example A) • • • Find the value of (9 – 5) + 2 Subtract 5 from 9 4+2 Add 4 and 2 6 So, the value of (9 – 5) + 2 is 6

Expressions (Example B) • • • Find the value of 9 – (5 +

Expressions (Example B) • • • Find the value of 9 – (5 + 2) Add 5 and 2. 9– 7 Subtract 7 from 9 2 So, the value of 9 – (5 + 2) is 2

More Expressions • Mrs. Wallace has 30 pencils. She gave 8 to the boys

More Expressions • Mrs. Wallace has 30 pencils. She gave 8 to the boys and 10 to the girls. • 30 – (8 + 10) • 30 – 18 • 12

Practice Expressions • • 12 – (3 + 4) (8 – 5) + 9

Practice Expressions • • 12 – (3 + 4) (8 – 5) + 9 32 + (8 + 2) 25 – (10 – 5)

Expressions with Variables • You can use a variable, or letter, to stand for

Expressions with Variables • You can use a variable, or letter, to stand for any number that you do not know. Then write the expression. • 8+m

Expressions with Variables • Fergus planted 3 rows in his garden in the morning.

Expressions with Variables • Fergus planted 3 rows in his garden in the morning. In the afternoon, he planted some more rows. What expression can you write to show the total number of rows he planted? • 3+n • How many rows did Fergus plant in all if he planted 4 rows in the afternoon? To find the value of the expression, replace n with the number of rows planted in the afternoon. • 3+n • 3 + 4 Replace n with 4 since he planted 4 rows in the afternoon • 7 • So, Fergus planted 7 rows in all

Expressions with Variables (Example A) • Find the value of 9 – c if

Expressions with Variables (Example A) • Find the value of 9 – c if c = 2. • 9 – c Replace c with 2 • 9 – 2 Subtract 2 from 9 • 7 • So, the value of the expression is 7.

Expressions with Variables (Example B) • • • Find the value of 8 +

Expressions with Variables (Example B) • • • Find the value of 8 + (m – 2) if m = 6. 8 + (m – 2) Replace m with 6 8 + (6 – 2) Subtract 2 from 6 8+4 12 So, the value of the expression is 12

Write an Expression • Eight people were at the party, then 7 more arrived.

Write an Expression • Eight people were at the party, then 7 more arrived. • Mike had 21 toy cars. He gave 4 of them to a friend, then got 5 more.

Write an Expression • The class collected 15 bags of trash, then collected 12

Write an Expression • The class collected 15 bags of trash, then collected 12 more bags. • A room had 25 desks. Five desks were added, then 3 were removed.

Write an expression. Choose a variable for the unknown. Tell what the variable represents.

Write an expression. Choose a variable for the unknown. Tell what the variable represents. • There were 24 students in the class, but some were absent. • Chris had 18 cards. Then he bought some more, but lost 7.

Write an expression. Choose a variable for the unknown. Tell what the variable represents.

Write an expression. Choose a variable for the unknown. Tell what the variable represents. • Susan had 24 stamps. She used some of the stamps to mail letters. • There were 4 pizzas at the party, then people ate 3 of them and ordered some more. • Nancy had 23 books. Her dad bought some books and gave Nancy all but 3 of them. • Carly starts with 37 pieces of candy. She gives one piece to each student in her class, and one to each of her 2 brothers.

Find the value of each expression • 5+2+6 • 17 – 9 – 6

Find the value of each expression • 5+2+6 • 17 – 9 – 6 • (8 – 7) + 1 • (25 – 10) + 8 • 6 – (3 + 2) • (62 – 40) + 31

Find the value of each expression if g =6, a = 12, and b

Find the value of each expression if g =6, a = 12, and b = 7. • g+9 • 50 – a • (g – 4) + 7 • a + 10 • 5 + (12 + g) • (b + 6) + a