||Janice has six pennies, six nickels, six dimes,
and six quarters. The easiest way to arrive at the
answer is to notice immediately that, since the
last number in the amount she has is 6, she must
have either six pennies or one penny. She can't
have just one penny, because then she would have
only one each of three other denominations, and
that can't add up to $2.46. So she must have six
of each denomination. She can't have six silver
dollars, because then she'd have more than $2.46.
And half-dollars are no longer in circulation.
Source:Barnes and Noble,
Mensa Presents Mind Games for Kids,p.14