The four-digit numeral 3AA1 is divisible by 9.
What digit does A represents?
Rule: A number is divisible by 9 if sum of its digits
is divisible by 9.
Examples:
9 has one digit 9 is divisible by 9
18 has two digits, 1 and 8 => 1 + 8 = 9 is divisible by 9
900 has three digits, 9, 0, 0. 9 + 0 + 0 = 9 is divisible by 9
Problem #2
Suppose all the counting numbers are arranged in columns as
shown below.
Under what column-letter will 100 appear?
A B C D E F G
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 _ _ _
Problem #3
A boy has the following seven coins in his pocket: 2 pennies,
2 nickels, 2 dimes, and 1 quarter. He takes out two coins, records
the sum of their values, and then puts them back with the other
coins. He continues to take out two coins, record the sum of their
values, and then put them back.
How many different sums can he record at most.
Problem #4
In a group of 30 students, 8 take French, 12 take Spanish and
3 take both languages.
How many students of the group take neither French nor Spanish?
Problem #5
Glen, Harry, and Kim each have a different favorite sport among
tennis, baseball, and soccer. Glen doe not like baseball or soccer.
Harry does not like baseball. Name the favorite sport of each person.
Problem #6
In the 'magic-square' below, five more numbers can be placed in the
boxes so that the sum of the three numbers in each row, in each
column, and in each diagonal is always the same.
What value should X have?
| 15 | __ | 35 |
| 50 | __ | __ |
| 25 | X | __ |
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