Mental math

by right hand, how to show number (7)?
 

• 
• 
• 
• 

By right hand, which one shows number 3?

• 
• 
• 
• 

By left hand, this one shows ...........

• 2

• 50

• 4

• 40

By right hand, this position shows......

• 1

• 6

• 10

• 60

By right hand, which numbers are shown in this sequence?

• 0,10,50,30

• 0,5,9,7

• 0,50,90,70

• 0,1,5,3

By right hand, how to show number 9?

• 
• 
• 
• 

By left hand, this show ........

• 8

• 80

• 4

• 40

By left hand, this show .......

• 2

• 20

• 60

• 6

By right hand, this position shows number ..........

• 90

• 9

• 5

• 50

By right hand, this show .....

• 1

• 10

• 5

• 50