Don't judge a book...
What is by its cover

What is an M&M

It's the product of the number of days in the week times itself
What is 49
7x7
Don't cross your eyes or...
What is or they'll stay that way

What is a bottle cap

The perimeter in inches of a square with 11-inch sides
What is 44
4x11
Once bitten...
What is twice shy

What is a razor

The number of years in a millennium divided by the number of years in a score
What is 50
1000/20
Hope for the best...
What is prepare for the worst

What is soap

It's the square root of the square root of 16
What is 2
sqrt(16) = 4
sqrt(4)=2
You can't make a silk purse...
What is from a sow's ear

What is a sponge

If 2x plus 4 equals 50, x equals this
What is 23
(50-4)/2