The sum of some value from the first row and and some value from the first column is given in the intersection box of these values. So: x+4=1 --> x=-3; y+4=-5 --> y=-9; x+e=-3+e=7 --> e=10; y+e=-9+10=n --> n=1; z+e=z+10=10 --> z=0; z+4=0+4=m --> m=4; m+n=4+1=5m+n=4+1=5. Answer: C.

Using the symmetry in the numbers involved (All formed using all possible combinations of 1,2,3,4), and we know there are 24 of them. We know there will be 6 each with the units digits as 1, as 2, as 3 and as 4. And the same holds true of the tens, hundreds and thousands digit. The sum is therefore ...

The numbers must be of the form ABCD13, where ABCD is any four-digit number between 3247 and 4585 inclusive.
ABCD cannot be 4586, as 458,613>458,600.

Therefore, the total number is 4585 - 3247 + 1 = 1339.

Answer E

In the correctly worked addition problem shown

AB
+BA
-----------
AAC

In the correctly worked addition problem shown, where the sum of the two-digit positive integers AB and BA is the three-digit integer AAC, and A, B, and C are different digits, what is the units digit of the integer AAC?

A. 9
B. 6
C. 3
D. 2
E. 0

In a certain deck of cards

In a certain deck of cards, each card has a positive integer written on it, in a multiplication game a child draws a card and multiplies the integer on the card with the next large integer. If the each possible product is between 15 and 200, then the least and greatest integer on the card would be A...

M is the sum of the reciprocals

M is the sum of the reciprocals of the consecutive integers from 201 to 300, inclusive. Which of the following is true?

(A) 1/3 < M < 1/2
(B) 1/5 < M < 1/3
(C) 1/7 < M < 1/5
(D) 1/9 < M < 1/7
(E) 1/12 < M < 1/9

A certain library

A certain library assesses fines for overdue books as follows. On the first day that a book is overdue, the total fine is $0.10. For each additional day that the book is overdue, the total fine is either increased by $0.30 or doubled, whichever results in the lesser amount. What is the total for a b...