My Mama Says ...
By The Numbers
20

Don't judge a book...

What is by its cover

20

It's the product of the number of days in the week times itself

What is 49 (7x7)

40

Don't cross your eyes or...

What is or they'll stay that way

40

If 2x plus 4 equals 50, x equals this

What is 23 (50-4)/2

60

Once bitten...

What is twice shy

60

The perimeter in inches of a square with 11-inch sides

What is 44 (4x11)

80

Hope for the best...

What is prepare for the worst

80

It's the square root of the square root of 16

What is 2 

100

You can't make a silk purse...

What is from a sow's ear

100

The number of years in a millennium divided by the number of years in a score

What is 50 (1000/20)