Mental Math

1) Start with the number of sides on an octagon.

2) Divide by 2

3) Multiply by 4

• 16

• 12

• 18

• 8

Tags

CCSS.3.OA.A.3

CCSS.3.OA.C.7

CCSS.3.OA.D.8

1) 6 + 12

2) minus 12

3) times 2

• 10

• 12

• 14

• 24

Tags

CCSS.3.NBT.A.2

CCSS.3.OA.A.3

CCSS.3.OA.D.8

1) take the sides in a hexagon

2) multiply by 9

3) minus 4

• 40

• 50

• 54

• 44

Tags

CCSS.4.NBT.B.5

CCSS.4.OA.A.2

CCSS.4.OA.A.3

1) take the number of sides in a triangle

2) multiply by the number of sides in a square

3) minus 6

• 8

• 5

• 6

• 7

Tags

CCSS.3.OA.A.1

CCSS.3.OA.A.3

CCSS.3.OA.D.8

1) 20 x 3

2) minus 12

3) plus 3

• 41

• 52

• 51

• 50

Tags

CCSS.3.NBT.A.3

CCSS.3.OA.A.3

CCSS.3.OA.C.7

CCSS.3.OA.D.8

1) Take the number of months in a year

2) Divide by 2

3) times 5

• 40

• 45

• 30

• 35

Tags

CCSS.3.OA.A.3

CCSS.3.OA.C.7

CCSS.3.OA.D.8

1) Take the number of sides in a quadrilateral

2) Multiply by 4

3) Add 10

• 25

• 23

• 29

• 26

Tags

CCSS.3.OA.A.3

CCSS.3.OA.C.7

CCSS.3.OA.D.8

1) 12 doubled

2) Plus 6

3) Times 5

• 120

• 112

• 150

• 125

Tags

CCSS.3.OA.A.3

CCSS.3.OA.C.7

CCSS.3.OA.D.8

1) 17 doubled

2) Plus 11

3) Divided by 5

4) Times 10

• 80

• 20

• 100

• 90

Tags

CCSS.3.OA.A.3

CCSS.3.OA.B.5

CCSS.3.OA.C.7

CCSS.3.OA.D.8

1) 9 x 3

2) Minus 2

3) Times 3

4) Plus 5

• 80

• 70

• 75

• 65

Tags

CCSS.3.OA.A.1

CCSS.3.OA.A.3

CCSS.3.OA.B.5

CCSS.3.OA.C.7